Thursday

December 18, 2014

December 18, 2014

Total # Posts: 28,251

**Maths**

tan18° = 55/x take over
*December 11, 2014*

**Precalculus**

the y-intercept is 4, so the height is 4 the x-intercept is 4/3, so the base is 4/3 area = (1/2)base x height = (1/2)(4)(4/3) = 8/3 square units
*December 11, 2014*

**Precalculus**

let side parallel to river be y let the other two sides be x each 2x + y = 1000 , ----> y = 1000-2x area = xy = x(1000-2x) = 1000x - 2x^2 if you know Calculus..... d(area)/dx = 1000 - 4x = 0 for a max of area 4x =1000 x = 250 y = 1000-2(250) = 500 so max area = xy = 250(500...
*December 11, 2014*

**Algebra !**

a + (b/100)a = 12 a( 1 + b/100) = 12 a - (b/100)a = 8 a( 1 - b/100) = 8 divide the top equation by the last one (1+b/100)/( 1 - b/100) = 12/8 = 3/2 2 + 2b/100 = 3 - 3b/100 times 100 200 + 2b = 300 - 3b 5b = 100 b = 20 back in a(1-b/100) = 8 a(1 - 20/100) = 8 a(1 - 1/5) = 8 a(4...
*December 11, 2014*

**Math**

If I were you , I would go with Ms Sue's answer of 5/16 since often lawyers don't tell the truth. btw, Ms Sue's last line is 16/16 - 11/16 = 5/16
*December 11, 2014*

**algebra**

short side ---- x each of other sides (must be isosceles) ---- 3x x + 3x + 3x = 112 I will let you finish it
*December 11, 2014*

**algebra**

v = -6000t + 70000
*December 11, 2014*

**Algebra 1 Ohio 8th grade standards**

since in the form y = mx + b, the slope of the line is m so for your line y = (1/2)x + 1, the slope is 1/2 But for perpendicuar lines, their slopes are opposite reciprocals of each other, so the slope of your new line must be -2/1 or -2 and the new equation must be y = -2x + b...
*December 11, 2014*

**Math**

"How much must they deposit NOW" isn't that present ? PV = 5500( 1 - 1.02^-20)/.02 = $89932.88
*December 11, 2014*

**math**

let the number of boys be 7x and the number of girls be 4x 7x - 4x = 21 3x = 21 x = 7 so there are 49 boys and 28 girls for a total of 77
*December 11, 2014*

**algebra**

so you have 2 ordered pairs of the type (brownies, cost) , (2000,1500) , (4000, 2000) slope = (2000-1500)/(4000-2000) = 500/2000 = 1/4 using the 2nd point, ... cost - 2000 = (1/4)(brownies - 4000) 4 C - 8000 = B - 4000 B - 4C = -4000 (checking if 1st point satisfies ... LS = ...
*December 11, 2014*

**Precal**

Assuming exponential decay amount = a e^(kt) where a is the initial amount, and t is number of years .8 = 1 e^(250k( ln .8 = ln e^(250k) ln .8 = 250k k = ln.8/250 after 600 years ? amount = 1 e^(600ln.8/250) = .5853 or appr 58.5% for half-life ? .5 = e^(ln.8 t/250) ln.5 = ln.8...
*December 11, 2014*

**Math**

7r + -5 = 7r - 5
*December 11, 2014*

**math**

normal rate: adult --- 14 child ---- 8 for holiday: adult -- 28 child -- 5/4(8) = 10 The rest of your post is quite confusing. What part of December is a school holiday in Malaysia?
*December 11, 2014*

**math**

How about this ? (5/6 - 2/3 + x)/3 = 1/4 1/6 + x = 3/4 x = 3/4 - 1/6 = 7/12 I agree with Damon, the wording is rather ambiguous.
*December 11, 2014*

**Sixth Grade Math**

you want the ratio of L : W to remain at 8 : 5 so 42/W = 8/5 8W = 210 W = 210/8 = 26.25 check: 42/26.25 = 1.6 = 8/5 Of course the ratio could have been expressed in more than one way, but whichever way you choose, the cross-product has to end up as 8W = 210 Looking over your ...
*December 11, 2014*

**Math**

Oh well, that changes everything. Notice that your lines do not line up as you intended, that is a fault of this format. If the bar is above the .63 then clearly that is your answer
*December 11, 2014*

**Math**

7/11 = .36363636... , the 36 repeats Those are poor choices for answers. First of all A and B are the same answer, rounded to one decimal would be .4 rounded to two decimals would be .64 rounded to three decimals wold be .636 so none of the choices are correct.
*December 11, 2014*

**algebra2**

so the hypotenuse of your right-angled triangle is 102 (ignoring the slack in the line) let the height be h sin 54.9° = h/102 h = 102sin54.9° = ...
*December 10, 2014*

**calculus**

limit ( √(x^2 + 7) - 4)/( √(x^2 - 8) - 1) , as x --> 3 my first step always is to actually sub in the approach value, sure enough, I get 0/0 That means the "eventually" my expression should factor. multiply top and bottom by (√(x^2 - 8) + 1) I ...
*December 10, 2014*

**Math**

let the length of the large rectangle be y let each of the parallel divider sides be x so we have 4x + 2y = 940 2x + y =470 y = 470 - 2x Area of whole field = xy = x(470-2x) = 470x - 2x^2 d(Area)/dx = 470 - 4x = 0 for a max of Area 4x = 470 x = 117.5 then y = 235 and the ...
*December 10, 2014*

**Ap calc**

let the distance run by the running player be x from the line of scrimmage. Let the distance between them be d In my diagram, I have a right-angles triangle with fixed side of 30, the other side (x+2.5) and the hypotenuse d, so that d^2 = (x+2.5)^2 + 30^2 2d dd/dt = 2(x+2.5) ...
*December 10, 2014*

**math**

first part is simply 40 choose 5 = C(40,5) = 658008 b) The leader can be picked in 8 ways, and then we have to choose 4 more from 39 = 8 C(39,4) = 658008 Are you surprised that the answers are the same ?
*December 10, 2014*

**math**

225+75+200-50+125 + x = 895
*December 10, 2014*

**D J HIGH SCHOOL SOST GOJAL PAKISTANmaths trignometry**

Did you make a diagram ? On mine I labeled the top of the observation point A and its bottom as B The farter boat as P and the closer boat as Q So we have two right-angled triangles with the angle at P as 30° and the angle at Q as 45° in triangle AQB , tan 45° = ...
*December 10, 2014*

**Calculus**

amount at the beginning = 5000 amount after 20 years = 5000 e^(.04(20)) = 11127.70 evaluated the "average value" as defined in your text book or notes. I don't know how it was defined for your course.
*December 10, 2014*

**Math**

Question is not clear. How is the interest rate compounded? When are payments made? What is that payment?
*December 9, 2014*

**Math**

f ' (x) = 3x^2 + 12 which is clearly positive for any value of x you give me. So, yes, you are correct
*December 9, 2014*

**CAL**

Why do you keep switching names ? As you can see from the previous replies there is a max at x = 1 form 0 to 3 for x = 1 y = 3 - 25 + 60 + 1 = 39 so the max is (1,39) the graph I gave you confirms this
*December 9, 2014*

**Derivative Test**

I did most of this in the previous post Here is a picture of your graph http://www.wolframalpha.com/input/?i=plot+y+%3D+3x%5E5+%E2%80%93+25x%5E3+%2B+60x+%2B+1
*December 9, 2014*

**Math**

no, points consist of ordered pairs of two numbers. ±1 and ±2 are the x's of the points. I told you what to do with those x's above, please read it.
*December 9, 2014*

**Math**

I am sure you meant: y = 3x^5 - 25x^3 + 60x + 1 dy/dx = 15x^4 - 75x^2 + 60 = 0 for your critical values 3x^4 - 15x^2 + 12 = 0 x^4 - 5x^2 + 4 = 0 (x^2 - 1)(x^2 - 4) = 0 x^2 = 1 or x^2 = 4 x = ± 1 OR x = ± 2 sub in those values of x in the original to get the ...
*December 9, 2014*

**7th grade math**

why are you repeating the questions? btw , the very last one is correct
*December 9, 2014*

**7th grade math**

#1 - correct , all you had to do is multipy 1 1/4 by 3 , sinc 9 helpings = 3 x 3servings #2 5 cm <----> 1500 ft 1 cm < ----> 500 ft, that is a scale #3, no need to convert, if you use the same units in each fraction 2.5/4.25 = 50/x 2.5x = 212.5 x = 212.5/2.5 = 85 ...
*December 9, 2014*

**Trigonometry**

Does this help ? http://www.wolframalpha.com/input/?i=plot+y%3D3cos%282x%29+%2C+y%3D-4sin%284x%29
*December 9, 2014*

**math**

by proper subsets I assume we would exclude the empty set So with the empty set there were 256 subsets for n elements, the number of subsets is 2^n 2^n = 256 but 256 = 2^8 so n = 8 and there were 8 elements in the set
*December 9, 2014*

**MATH HELP ASAP!**

Time = Interest/(principal x rate) = 550/(1000(.05) = 550/50 = 11 yup, its 11
*December 9, 2014*

**Pre-Algebra can you please help?!**

interest from simple interest = 400(.045)(3) = 54 interest fromt he compound account = 450(1.032)^3 - 450 = 44.60 total interest = 54 + 44.60 = 98.60 , which is D
*December 9, 2014*

**Math**

i = .05004/12 = .00417 n = 25(12) = 300 let the monthly payment be p p(1 - 1.00417^-300 )/.00417 = 292649 the monthly payment is $ 1711.48
*December 9, 2014*

**math**

I entered your date into this wonderful website http://davidmlane.com/hyperstat/z_table.html and got 21.19 %
*December 9, 2014*

**Math**

you are given 2 ordered pairs (5 , 1050) and (9,900) slope = (900 - 1050)/(9-5) = - 150/4 = - 75/2 N = (-75/2)C + b using (5,1050) 1050 = (-75/2)(5) + b 1050 + 375/2 = b b = 2475/2 N = (-75/2)C + 2475/2 or N = -37.5C + 1237.5 where N is the number sold and C is the price of ...
*December 9, 2014*

**math**

Don't know if they teach you algebra where you are. Think of the points being split into 9 parts, where Alan would get 2 parts, Gil would get 3 parts and Debbie 4 parts So for her 2 parts deb got 114400/4 = 28600 per part so the total number of points = 9(28600) = 257400 ...
*December 9, 2014*

**Math**

so treat your data as two ordered pairs (0,97000) and (6,109000) Just like in a normal x-y equation, slope = (109000-97000)/(6-0) = 12000/6 = 2000 using (0, 97000) , which would be the y-intercept y = 2000x + 97000
*December 9, 2014*

**Math**

g(x) = 15x + 9 - 9-12 = 3(5x+3) - 21 = 3 f(x) - 21 or g(x) = 15x + 15 - 15 - 12 = 5(3x +3) - 15 - 12 = 5 f(x) - 27
*December 9, 2014*

**Algebra**

I don't blame you for being lost, since the question is poorly worded. Since they started off my talking about linear equations, I had assumed that all the given points lie on the same straight line. But they do not. anyway... suppose we take the first two points (5,1) and...
*December 9, 2014*

**Euler's method help in Calculus?????**

This is tedious work I found an excellent youtube for you where they solve a problem very similar to yours. I assume your text or your notes contain the basic original formula for Euler's Method I suggest you pause the video at critical points and make the necessary ...
*December 9, 2014*

**math**

Let Sam's age 7 years ago be s let Tom's age 7 years ago be t So s+7 + t+7 = 27 s+t = 13 ---> t = 13-s "seven years ago, tomas was three years more than one-fourth as old as sam" --- t = (1/4)s + 3 13-s = (1/4)s + 3 times 4 52 - 4s = s + 12 -5s = -40 s = 8...
*December 9, 2014*

**Math**

how about 130 and 121 ? I would not count those starting with 0 e.g. 031 is a 2 digit number
*December 8, 2014*

**Math**

Larry , you are right and observant to catch my error. So just make the necessary changes here is a neat trick to make an inverse answer is correct (which I did not do) pick any "nice" x value and find y e.g. x = 0 y = (9-0)/(0-9) = -1 now put that into the inverse ...
*December 8, 2014*

**Math**

let y = (9-8x) / (10x-9) for the inverse, interchange the x and y variables ---> x = (9-8y)/(10y-9) 10xy - 9x = 9 - 8y 10xy - 8y = 9+9x y(10x - 8) = 9+9x y = (9+9x)/(10x - 8) f^-1 (x) = (9x+9)/(10x-8)
*December 8, 2014*

**General Calculus Question**

No, notice the highest powers are NOT the same, so my explanation is not valid. as x --> inf √(x^2 - 2x) ---> x e.g. pick x = 1000000 and use your calculator to see so the numerator ---> 3x^2 the denominator ----> x so the limit is inf.
*December 8, 2014*

**General Calculus Question**

did you mean something like lim (4x^2 -2√x)/(3x^2 + 5√2x) of course it could only approach + inf , or else the root terms would be undefined. Other than that, the same rule applies the limit would be 4/3
*December 8, 2014*

**General Calculus Question**

as x ---> inf and the top and bottom have the same highest power, then those terms will determine the limit See my answer to a similar question by James at 11:06
*December 8, 2014*

**Math**

divide top and bottom by x^2 to get lim (7/x + 6)/(7 + 6/x) as x ---> inf both 7/x and 6/x ---> 0 so we are left with (0 + 6)/(7 + 6) = 6/7
*December 8, 2014*

**Math**

use your rules of logs logx + logx + logx = 3 log (x)(x)(x) = 3 log x^3 = 3 3logx = 3 logx = 1 or x = 10^1 = 10 check: What is log1010 ? isn't it 1 ?
*December 8, 2014*

**math**

you want your ball to be #7 AND black There is only one such ball prob (black and #7 ) = 1/10
*December 8, 2014*

**APCalculus**

lets look at your graph first of all http://www.wolframalpha.com/input/?i=plot+y%3D2sin%28x%29-cos%5E2%28x%29 clearly no vertical or horizontal asymptotes you had that, your y-intercept is correct symmetry: about each vertical line passing through a max or a min I disagree ...
*December 8, 2014*

**Math (Simplifying Fraction)**

= ( 1/x + 4/x^2) / (1 - 16/x^2) multiply top and bottom by x^2 = ( 1/x + 4/x^2) / (1 - 16/x^2) * (x^2/x^2) Since I am multiplying by 1, I am not changing the value of my fraction , simply its appearance = (x+4)/(x^2 - 16) = (x+4)/( (x+4)(x-4) ) = 1/(x-4) , x ≠ -4 (or ...
*December 8, 2014*

**APCalculus**

taking your typing at face value the way you typed it your domain is correct as a matter of fact: "I got some: domain: (-infinity, infinity) y-intercept: y=4 Vertical asymptotes: none Horizontal asymptotes: none Symmetry: y-axis F'(x): 2/3x^3-4x Critical numbers: x=0...
*December 8, 2014*

**Math**

you were right to factor it, but your second part is totally bogus I also think you placed brackets in the wrong place, probably should have been: 6/(x^2+5x+6) + 9/(x+3) = 6/( (x+2)(x+3) ) + 9/(x+3) we now need a common denominator which is (x+2)(x+3) = 6/((x+2)(x+3)) + 9(x+2...
*December 8, 2014*

**math**

ones digit --- x tens digit ---- 2x thousands --- 4x hundreds -----y x+2x + 4x + y = 19 y = 19-7x but x and y must be single digit positive integers. let x = 1, then y = 12 , not possible let x = 2, then y = 5 The number is 8542 let x = 3, then y = 19-21 = negative, no good ...
*December 8, 2014*

**Math**

(x-(1/x))/(1-(1/x)) = ( (x^2 - 1)/x) / ( (x-1)/x) = ( (x-1)(x+1)/x ) * (x/(x-1)) = (x-1)(x+1)/(x-1) = x+1 , x ≠0,1
*December 8, 2014*

**math**

I assume you mean: 25 = (748/7)^x take log of both sides log25 = log(748/7)^x = x log(748/7) = x(log748 - log7) x = log25/(log748-log7) get out your calculator and push some buttons I got appr .689
*December 8, 2014*

**Math**

1. cos^-1(sin(π/2) we know sin π/2 = 1 so cos^-1 (sin π/2) = cos^-1 (1) = 0 (because cos 0 = 1 ) 2. this one is easy, since arccos is the same as cos^-1 the answer is obviously 7π/2 However, they might just want a reduced answer since cos 7π/2 = cos 3...
*December 8, 2014*

**math**

Let the cost of John's 4 pencils and 3 erasers be x then the cost of Smith's 8 pencils and 6 erasers is 2x , notice twice as many cost of Smiths 3 pens --- y cost of John's 6 pens ---- 2y , notice twice as many pens Johns cost = 2y + x Smith's cost = y + 2x y...
*December 8, 2014*

**Calculus**

First we have to find their intersection to establish the boundaries. x^2 - 6 = 12 - x^2 2x^2 = 18 x^2 = 9 x = ± 3 so we have a closed region from -3 to +3 the height of the region for that domain = 12-x^2 - (x^2 - 6) = 18 - 2x^2 area = [integral] (18-2x^2)dx from -3 to...
*December 7, 2014*

**math**

So the distance between the two trains is changing at a rate of 100 km/h, (the sum of their speeds) so it will take them 100/100 or 1 hour to collide. In the meantime, the fly is merrily flying back and forth at 75 km/h, so in the 1 hour it would have simply traveled 75 km. ...
*December 7, 2014*

**Math**

1(1 + .024/12)^(12t) = 2 , any starting sum will do, I started with $1 and want to end up with $2 1.002^(12t) = 2 take log of both sides log(1.002^(12t) ) = log2 rules of logs .... 12t log 1.002 = log 2 12t = log2/log1.002 = 346.92.. t = 346.92/12 = 28.91
*December 7, 2014*

**math**

amount left = a (.5)^(t/14.9) , where a is the initial amount, and t is the time in hours a) sub in t = 48 amount left = a(.5)(48/14.9) = .1072a = appr 10.72% of what you started with b) can't be answered since you did not say what they started with. set 1 = a(.5)^(t/14.9...
*December 7, 2014*

**MATH**

good grief ! I think you posted the same question about 6 times tonight. Please look back before posting the same question again http://www.jiskha.com/display.cgi?id=1417998282
*December 7, 2014*

**Calc I**

your derivative will be the slope and since (π/6,1) lies on the curve, slope of tangent = 8cosπ/6 sinπ/6 = 8(√3/2)(1/2) = 2√3 ( you might recall that sin 2x = 2sinxcosx so 8sinxcosx = 4(2sinxcosx) = 4 sin2x then slope = 4sin(π/3) = 4√3/2...
*December 7, 2014*

**Algebra 1**

so your two points are (0,2) and (2,8) where (0,2) is the y-intercept slope = (8-2)/(2-0) = 3 without further ado y = 3x + 2
*December 7, 2014*

**Pre-Cal**

done , check back
*December 7, 2014*

**Pre Cal**

done, check back
*December 7, 2014*

**Pre-Calc**

I assume we are solving this equation ? by rules of logs .... log( (x-6)(x+3) ) = 1 10^1 = (x-6)(x+3) x^2 - 3x - 18 = 10 x^2 - 3x - 28 = 0 (x-7)(x+4) = 0 x = 7 or x = -4 , but to be defined in log(x-6), x > 6 so x = 7
*December 7, 2014*

**Calculas**

Did you notice that in the "Related Questions" below I answered a similar question back in 2008. All you have to do is change the numbers http://www.jiskha.com/display.cgi?id=1204511609
*December 7, 2014*

**Calculas**

have not seen that variation of the popular "make a box" question before. Made a diagram showing the net of the box with a lid. let the sides of the square to be cut out be x cm the the width of the box is 72 - 2x let the length of the box be y cm According to my ...
*December 7, 2014*

**Calculas**

Let the size of the cut-out square be x inches so the base of the box is (19-2x) by (19-2x) and the height is x V = x(19-2x)^2 = x(361 - 76x + 4x^2) = 4x^3 - 76x^2 + 361x dV/dx = 12x^2 - 152x + 361 = 0 for a max of V x = (152 ± √5776)/24 = (152 ± 76)/24 = ...
*December 7, 2014*

**Math - Differentiate**

No sure what you are "solving" From your subject title, should we conclude you want to differentiate ?? if so, then f ' (x) = 3x^2/(x^3 + 5) + 6
*December 7, 2014*

**Math**

the vertex of your parabolic path is (7,21) so y = a(x-7)^2 + 21 but (0,0) lies on it, so 0 = a(0-7)^2 + 21 0 = 49a + 21 49a = -21 a = -21/49 = -3/7 so y = (-3/7)(x - 7)^2 + 21
*December 7, 2014*

**Calc I**

I haven't got a clue how you came up with that first derivative. f(x) = (4t+1)^(1/2) f ' (x) = (1/2)(4t+1)^(-1/2) (4) = 2(4t+1)^(-1/2) f '' (x) = -1(4t+1)^(-3/2) (4) = -4(4t+1)^(-3/2) or = -4/(√(4t+1)^3 ) f '' (2) = -4/√9^3 = -4/27
*December 7, 2014*

**Factoring**

If you expand your answer, you don't get back what you started with. So you knew you were wrong. the common factor is 7, you had that correct answer: = 7(2z^2 - 7z + 35)
*December 7, 2014*

**Calc I**

your answer of 4(x^2+x^3)^3 * (2x+3x^2) is not incorrect, you just didn't go far enough 4(x^2+x^3)^3 * (2x+3x^2) =4(x^2 + x^3)(x^2 + x^3)(x^2 + x^3)(2x + 3x^2) = 4(x^2)(1+x)(x^2)(1+x)(x^2(1+x)(x)(2+3x) = 4x^7 (1+x)^3 (2+3x) Your "correct" answer is NOT correct
*December 7, 2014*

**solve**

snow storm speed --- x mph rain storm speed ---- 2x mph 168/x - 168/2x = 3 times 2x 336 - 168 = 6x x = 168/6 = 28 So he went 28 mph in the snow storm and 56 mph in the rain check: snow: 168/28 = 6 rain: 168/56 = 3 , so 3 hours less than in the snow
*December 7, 2014*

**Math word problem**

how about 18 nickels and 1 dime or 9 dimes and 10 penny or .. suppose we restrict ourselves to p pennies, n nickels, d dimes, q quarter then we need integer solutions to pennies + nickels = 100 p + 5(19-p) = 100 p + 95 -5p = 100 -4p = 5 --->no integer solution pennies + ...
*December 7, 2014*

**problem solving**

The question is much too vague. I assume that p is the perimeter (p is not defined) Are the sides to be integer value? Are the triangles scalene ? , isosceles ? The largest triangle of course would be an equilateral triangle with sides 100/3 each and an area of (1/2)(100/3)^2 ...
*December 7, 2014*

**problem solving**

Wow rectangles? squares? triangles? hexagons? .... star-shaped things convex septagons ? ...
*December 7, 2014*

**problem solving**

number of blocks --- x cost per block --- y 1.05xy = 315 xy = 300 without sales tax the cost would have been (x+6)y = 315 so divide the two equations: ( (x+6)y)/(xy) = 315/300 (x+6)/x = 21/20 21x = 20x + 120 x = 120 , then y = 2.5 He bought 120 blocks at $2.50 each check: 120(...
*December 7, 2014*

**calculus**

V = lwh dV/dt = lw dh/dt + lh dw/dt + wh dl/dt you are given all the values, just plug in and evaluate
*December 6, 2014*

**Math help**

Since the angle of incidence is equal to the angle of reflection in the mirror you have tow similar right-angled triangles. Thus we can use our good ol' fashioned ratios x/7.5 = 5.5/3 3x = 41.25 x = 13.75 or 13.8 ft to the nearest tenth of a foot
*December 6, 2014*

**Algebra**

I don't think you are using the concept of the "inverse of a function" in the proper way, you are just solving the equation for c d = .15c - 1.5 .15c = d + 1.5 c = (d+1.5)/.15 now plug in d = 18 c = (18+1.5)/.15 = 130 We could have just plugged in d = 18 in the ...
*December 6, 2014*

**calculus**

you had ∫ e^(8x) (e^(8x) + e^(-8x) )/2 dx which is = ∫ ( e^(16x) + e^0 )/2 dx = (1/2)(1/16)e^(16x) + (1/2)x | from 0 to 1/16 = (1/2)(1/16) e^1 + 1/32 - (1/2)(1/16)e^0 - 0 = (1/32)e or = e/32
*December 6, 2014*

**capacity problems**

ummmh, what is 2 x 80 ??
*December 6, 2014*

**7th grade math**

#4 There are only 6 students, so just take (5/6)(120) = 100 so 100 prefer pepperoni #6. Taylor/Kate = 3/2 Taylor/120 = 3/2 2 Taylor = 360 Taylor = 180 #9 d) (-2/5) / (-1/5) = (-2/5)(-5/1) = 10/5 = 2 The others are correct
*December 6, 2014*

**algebra**

let the speed of the plane in still air be x mph let the speed of the wind be y mph then 570/(x+y) = 3 --->3x + 3y = 570 x + y = 190 570/(x-y) = 5 ---> 5x - 5y = 570 x - y = 114 add them 2x = 304 x = 152 back in the first: 152 + y = 190 y = 38
*December 6, 2014*

**algebra**

If you are taking Calculus .... E ' (v) = -.032v + 1.408 = 0 for max of E .032v = 1.408 v = 44 E(44) = ....just sub in
*December 6, 2014*

**maths**

Please proof-read your post before sending it route = root squre = square i/3 = 1/3 ?? So if 1/3 of the diagonal is 3√2, then the diagonal is 9√2 let the side of the square be x x^2 + x^2 = (9√2)^2 2x^2 = 162 x^2 = 81 x = √81 = 9
*December 6, 2014*

**Algebra**

notice you can take out r^2 as a common factor r^2(15.64 + 4.16) = 235.619 19.8 r^2 = 235.619 r^2 = 11.899945... r = appr 3.45 to the nearest hundredth
*December 6, 2014*

**Math Trig**

sec Ø = -13/5 in quad II so cosØ = -5/13 x = -5, r = 13 and y = +12 sinØ = 12/13 cotØ = -5/12
*December 5, 2014*

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