Monday

November 30, 2015
Total # Posts: 31,850

**Calculus**

The rectangle is 2x by 3x with the semicircle on top of the 2x side Since there is a semicircle on top of the rectangle, the area = rectangle + semicircle = basexheight + (1/2)π x^2 = (2x)(3x) + π x^2/2 = 6x^2 + πx^2/2 perimeter = (1/2)(2πx) + 2x + 2(3x...
*September 25, 2015*

**math**

Poorly worded question, since there is no maximum value of y = x^4 - 8x http://www.wolframalpha.com/input/?i=plot+y+%3D+x%5E4+-+8x suppose we blindly proceed as usual ... dy/dx = 4x^3 - 8 = 0 for a max/min 4x^3 = 8 x^3 = 2 x = 2^(1/3) = appr 1.2599 subbing that in gives us y...
*September 25, 2015*

**math**

Intuitively, one should conclude that the sides would be equal, let's prove it let one side by x, then the other is √(144 - x^2) area = (1/2)x√(144-x^2) = (1/2)x(144-x^2)^(1/2) d(area)/dx = (1/2)[ x(1/2)(144-x^2)^(-1/2) (-2x) + (144-x^2)^(1/2) ] = 0 for a max ...
*September 25, 2015*

**P6 maths**

looks like I can't tell Mary and Amy apart.
*September 25, 2015*

**P6 maths**

mary's stamps --- m Amy's stamps ---- a .4m = .75a 40m = 75a m = 75a/40 = 15a/8 after giveaway Mary has .75m Amy has a + .25m a + .25m - .75m = 90 a - .5m = 90 2a - m = 180 2a - 15a/8 = 180 16a - 15a = 1440 a = 1440 m =2700 check my arithmetic
*September 25, 2015*

**Calculus 1**

Here is what your curve looks like http://www.wolframalpha.com/input/?i=plot+y+%3D+%7Cx%7C%2F%28sqrt%285-+x%5E2%29%29 notice that -√5 < x < √5 is our domain, with x = ±√5 as asymptotes Since (2,2) lies in quadrant I I will use y = x/√(5 - x...
*September 25, 2015*

**Math**

Numbers "dividing evenly" has nothing to do with the numbers being even. A number is said to divide into another evenly, if there is a zero remainder after the division. e.g. 15 ÷ 3 = 5 , (note none of the numbers are even) 15 is evenly divisible by 3 but 18 &...
*September 24, 2015*

**Math**

I assume you meant: (3/4) /8 + (1/3) /4 confirm please
*September 24, 2015*

**Solving Linear Equations (Math)**

width ---- x "The length of a rectangle is 5m shorter than three times the width" ---> length = 3x - 5 2x + 2(3x-5) = 46 should be easy to solve, go for it
*September 24, 2015*

**Math**

no 1+1 = 2 , which is not in the set of {0,1}
*September 24, 2015*

**math for managers**

What do you want done ? We are looking at the equation of a straight line
*September 24, 2015*

**Math**

amount at 5% --- x solve for x: .05x + .1(1800-x) = 165
*September 24, 2015*

**math**

prob(correct) = 1/5 prob(not correct) = 4/5 a) to have exactly 5 correct = C(12,5) (1/5)^5 (4/5)^7 = appr .05315 b) prob(2 correct) = C(12,2) (1/5)^2 (4/5)^10 = ... c) 4 or fewer correct ---> 0 correct + 1 correct + 2 correct + 3 correct + 4 correct d) to get 75% he needs ...
*September 24, 2015*

**Calculus**

What method are you using to solve a cubic, since there is no simple "formula" method ? your two answers do not satisfy the equation here is what Wolfram has http://www.wolframalpha.com/input/?i=solve+x%5E3-3x%2B3%3D0 click on "approximate forms" to see one...
*September 24, 2015*

**Algebra 2**

no you were correct at 8/√2 * √2/√2 = 8√2/(√2)^2 , but √2^2 is equal to 2 = 8√2/2 = 4√2 If you have any others, why not check your answer using a calculator e.g. 8/√2 = 5.6568... 4√2 = 5.6568... my answer is correct
*September 24, 2015*

**calculus**

with all due respect what are we doing here ?
*September 24, 2015*

**Math M131A**

end of first bounce it dropped 108 ft during the second bounce it went up and down (1/3) of 108 or 2(1/3)(108) = 72 during the third bounce it went 2(1/3)(72) = 48 during the fourth bounce it went 2(1/3)(48) = 32 so after 4 bounces it went 108+72+48+32 = 260 make a sketch, ...
*September 24, 2015*

**Precalculus**

if x+6 is a factor, then f(-6) must equal zero test if it is
*September 24, 2015*

**Precalculus**

f(x)=2x^2-4x+3 f(x+h) = 2(x+h)^2 - 4(x+h) + 3 = 2(x^2 + 2hx + h^2) - 4x - 4h + 3 = 2x^2 + 4hx + 2h^2 - 4x - 4h + 3 f(x+h)-f(x) = 2x^2 + 4hx + 2h^2 - 4x - 4h + 3 - 2x^2 + 4x - 3 = 4hx + 2h^2 - 4h notice all the "non-h" terms dropped out. This MUST always happen. If ...
*September 24, 2015*

**maths**

I think he means 1 1/2 m and 1 1/3 m - Usually we leave a space between the numbers in mixed fractions - Secondly, in the metric system we would not use such a fraction, it would be either 1.5 m or 150 cm Height of human is expressed in cm in the metric system. - Thirdly, &...
*September 24, 2015*

**Precalculus**

i -3
*September 24, 2015*

**Maths**

speed = distance/time = 7.5 km / 27.5 min = 7500 m / (27.5*60) seconds = 50/11 m/s
*September 24, 2015*

**MATH (vector addition)**

my diagram consists of a right-angled triangle with a hypotenuse of 4, a height of 2 and a horizontal of x by Pythagoras, x^2 + 2^2 = 4^2 x = 2√3 , his actual swimming speed direction: sinØ = 2/4 Ø = 30°
*September 24, 2015*

**Precalculus**

Since we can sub in any x we feel like without getting anything undefined, the domain is the set of real numbers
*September 24, 2015*

**Precalculus**

He has 10 km of fence to fence in a field on a farm ?? Anyway ... Let each of the lengths be y let each of the shorter sides by x so we need 2y + 3x 2y + 3x = 10000 ---> y = (10000-3x)/2 area = xy = x(10000-3x)/2 = 5000x - (3/2)x^2 d(area)/dx = 5000-3x = 0 for a max of area...
*September 24, 2015*

**kv**

so he has gone 4 km north and 3 km east by Pythagoras .....
*September 24, 2015*

**kumasi polytechnic**

term(8) - term(4) = 20 a + 7d - a - 3d = 20 4d = 20 d = 5 term(8) = (3/2)(term(4)) a+7d = (3/2)(a+3d) 2a + 14d = 3a + 9d 5d = a a = 25 a=25 ---> first term d = 5 check: sequence is: 25, 30, 35, 40, 45, 50, 55, 60, .. term(8) = 60, term(4) = 20 is 60-40 = 20 ? yes is 60 = (3...
*September 24, 2015*

**algebra**

I don't understand why you are putting in those strange denominators. 1. mercury's velocity = 29.74 miles/second = 29.74(60) or 1784.4 miles/minute = 1784.4(60) or 107064 miles/hour so 107064 mph there is no fraction involved, so why create one? 2. how much greater is ...
*September 24, 2015*

**Math**

Areas of similar figures are proportional to the square of the sides area of larger top = 54x36 = 1944 area of kid's desk/1944 = (2/3)^2 = 4/9 area of kid's desk = (4/9)(1944) = 864 inches^2 perimeter of big top = 2(54+36) = 180 perimeter of kid's top = (2/3)(180...
*September 24, 2015*

**math**

multiply each term by v 7v = -2 + 4v 3v = -2 v = -2/3 if you meant: 7 = -2/(v+4) multiply both sides by v+4 etc
*September 23, 2015*

**math**

at start, number of dimes --- x number of quarters -- x after give-away: dimes = x quarters = x-15 10x + 25(x-15) = 2250 solve for x
*September 23, 2015*

**Calc- Limits**

your sentence makes no sense to me
*September 23, 2015*

**precalc**

here is my sequence of button-pushings: 17.2 - .3 = ----> 16.9 x 2 x π ÷ 3 = ---> 35.3952... cos = ----> -.66913... x 10 + 50 = -----> 43.308...
*September 23, 2015*

**precalc**

I got 43.3 on mine show your steps so I can find your error. btw, did you switch to radians ?
*September 23, 2015*

**math**

rate of first trip --- x mph rate of return trip = x+22 mph 6x = 4(x+22) solve for x , then evaluate 6x
*September 23, 2015*

**Math**

Assuming a normal speed of about 100 Km/h the number has to be only about 200 more 26962 + 200 = 27162 since the 2 leading digits can't change, it could only be 27172 The difference is 210 km, which would be a speed of 105 km/h, which is very reasonable
*September 23, 2015*

**Algebra 2**

let smaller window be x by x let the larger window be (x+5) by (x+5) so: x^2 + (x+5)^2 = 1025 expand and solve the quadratic
*September 23, 2015*

**Geometry**

Didn't have to do what I did, thought I had to find the equation of your circle Why not just find the length of the diameter, then perimeter = πr = 10π which answer approximates that ?
*September 23, 2015*

**Geometry**

centre is midpoint of the given line, centre is ( (1+7)/2 , (2-6)/2 ) = (4,-2) radius is distance from (1,2) to (4,-2) = √(3^2 + (-4)^2) = √25 = 5 carry on
*September 23, 2015*

**algebra**

bars sold by Tim ---- x Maria ----> 2x - 7 solve : x + 2x-7 = 137
*September 23, 2015*

**algebra**

middle number --- x 1st number ---- x-2 3rd number --- x+2 middle + larger > smaller by 21 middle + larger = smaller + 21 x + x+2 = x-2 + 21 x = 17 the three numbers are 15, 17, 19 check: sum of middle + larger = 17+19 = 36 the smaller = 15 is 36>15 by 21 ? , looks good
*September 23, 2015*

**Algebra 2**

4(x-6)^2 = x^2 Normally I would expand this, but since both sides are perfect squares .... take √ of both sides 2(x-6) = x 2x - 12 = x x = 12
*September 23, 2015*

**Math**

Hint: What have you learned about the slopes of perpendicular lines ? in the form y = mx + b, what does the m stand for ?
*September 23, 2015*

**Math**

show the steps you had for this simple equation
*September 23, 2015*

**Maths**

√(a^3) = (a^3)^(1/2) = a^(3/2)
*September 23, 2015*

**error - Math**

sarha's answer is not correct place the tree at the origin, so the bottom-left tree is at (-3,-2) the top-right tree is at (4,1) so the base of the rectangle is 7 the height is 3 perimeter = 2(7) + 2(3) = 20
*September 23, 2015*

**Math**

let x = .151515... times 100 100x = 15.151515... subtract them: notice the decimals line up and will subtract to get zeros 99x = 15 x = 15/99 = 5/33 check with your calculator by dividing 5 by 33
*September 23, 2015*

**maths**

I assume you meant 4.5 : 3.6 : 1.8 times 10 = 45 : 36 : 18 divide by 9 = 5 : 4 : 2
*September 23, 2015*

**math**

If GP, then (5x-3)/(x+3) = (7x+3)/(5x-3) 25x^2 - 30x + 9 = 7x^2 + 24x + 9 18x^2 - 54x = 0 6x(3x - 9) = 0 x= 0 or x = 3 if x = 0 3rd term = 3 4th term = -3 5th term = 3 .. 1st term = 3 2nd term = -3 sum of any even number of terms = 0 if x = 3, 3rd term = 6 4th term = 12 5th ...
*September 23, 2015*

**Algebra 1**

Yes, they are both x^2y the first term has 8 of them , the second has -5 of them
*September 23, 2015*

**maths**

Make a sketch Label the top of the tower as P and its base Q Label the first position of observer as A, his second position as B Join the straight line ABQ In triangle ABP, angle A = 30 angle ABP = 120 thus angle APB = 30, making AB = BP In triangle PBQ sin60 = PQ/30 PQ = ...
*September 23, 2015*

**Algebra**

it was translated 7 units to the right and 4 units up
*September 23, 2015*

**MATH**

You will need brackets around the denominator to obtain the proper order of operations your second fraction factors to 4y^2/((x-1)(x+1)) so the LCD is (x-1)(x+1) or the original x^2 - 1 so you have -3y(x+1)/(x^2 - 1) and 4y^2/(x^2 - 1)
*September 23, 2015*

**MATH**

type it this way: (h^2-k^2)/(h^4-k^4) / ( (h-k)/(h^2+k^2) ) = (h^2-k^2)/(h^4-k^4)((h^2+k^2)/(h-k) ) = (h+k)(h-k)/((h^2 + k^2)(h+k)(h-k)) ((h^2+k^2)/(h-k)) = 1/(h-k) , h ≠ k
*September 23, 2015*

**Trigonometry**

r^2 = 18^2+24^2 .. r = 30 cosØ = x/r = 18/30 = 3/5
*September 22, 2015*

**needs physics tutor- Math**

my physics skills are rusty
*September 22, 2015*

**Math**

the pieces must be 2x and 3x units long 2x + 3x = 60 you finish it, can't be any easier.
*September 22, 2015*

**Geometry**

I think you meant centre ON the line 5x-3y = 12 let the centre be (x,y) or (x,(5x-12)/3 ) if tangent to both axes, then x = y x = (5x-12)/3 3x = 5x - 12 x = 6 then y = (30-12)/3 = 6 and the radius is 6 (x-6)^2 + (y-6)^2 = 36 check: http://www.wolframalpha.com/input/?i=+%28x-6%...
*September 22, 2015*

**Algebra**

How are you doing these ?? #1 , (0,3) a sollution to y = x+3 Left Side = y = 3 Right Side = x+3 = 0+3 = 3 LS = RS So, YES, (0,3) lies on y = x+3 #2 (1,4) a solution to y = -2x ?? LS = 4 RS = -2(1) = -2 ≠ 4 So NO #3 y = x-4 for (6,3) ---> is 3 = 6-4 , NO for (4,0) ---&...
*September 22, 2015*

**algebra**

x^2-8x+12 can you think of 2 numbers which when multiplied will get you 12 , and when added will get you - 8 ? 3a^3-27a take out a common factor of 3a, and you are left with an obvious difference of squares 4y^2-9 a very obvious difference of squares
*September 22, 2015*

**math**

what is a ds decimal ? "The hundredths digits is twice the tenths digit is the GCF 18 and 27." - makes no sense to me. please proof-read your post
*September 22, 2015*

**mshweshwe high school**

a = 5 v = 5t + c at t=0 , v = 0, so c =0 v = 5t s = (5/2)t^2 + k again, when t=0,s=, thus k=0 so we have s = (5/2)t^2 when t=6 s = (5/2)(36) = 90 insert the necessary units and state your conclusion
*September 22, 2015*

**Math**

x(t) = 3.2√tan(5t) = 3.2(tan(5t))^(1/2) x ' (t) = 3.2(1/2)(tan(5t))^(-1/2) (5sec^2 (5t) ) plug in t = 1.5 - make sure your calculator is set to radians
*September 21, 2015*

**Calculus**

use the quotient rule f ' (x) = ( (1)(x+1)^(1/2) - x(1/2)(x+1)^(-1/2) )/(x+1) = (1/2)(x+1)^(-1/2) (2(x+1) - x )/(x+1) = (1/2)(x+2)/(x+1)^(3/2) or = (x+2)/(2(x+1)^(3/2 )
*September 21, 2015*

**Finance**

return on stock = 289+35 = 324 profit = 24 rate of return = 24/300 = .08 = 8%
*September 21, 2015*

**Algebra**

I read it as: (2x)(2^4)/(2^3) = 2^6 2x(2) = 64 x = 16
*September 21, 2015*

**Algebra**

by definition |anything| ≥ 0 so no solution
*September 21, 2015*

**geometry**

I'll do #2, you do the others 2. let the endpoint be K(x,y) (x+9)/2 = 5 x+9 = 10 x = 1 (y - 5)/2 = -2 y-5 = -4 y = 1 K is (1,1) check: midpoint of JK = ( (9+1)/2 , (-5+1)/2) = (5,-2) as given
*September 21, 2015*

**algebra**

what is the value of 4x^2 + y^2 ? all depends on the values of x and y
*September 21, 2015*

**Math**

7.560 x10^3
*September 21, 2015*

**Math**

if f(x)=x^2+5x+6 then -2f(x/11) = -2( (x/11)^2 + 5(x/11) + 6) you want the zeros of that ... -2[x^2/121 + 5x/11 + 6] = 0 x^2/121 + 5x/11 + 6 = 0 , I think you had it that far times 121 x^2 + 55x + 726 = 0 (x+22)(x+33) = 0 x = -22 or x = -33
*September 21, 2015*

**Math**

well, 2^1 = 2 2^2 = 4 2^3 = 8 2^4 = 16 2^5 = 32 so what is your interpretation?
*September 21, 2015*

**Math**

the way I read it, 5 years at 5% comp. monthly, then 5 years at 3% comp. monthly amount = [100(1.0041666...^60 - 1)/.0041666...](1.0025^60) + 100(1.0025^60 -1)/.0025 = 7899.70 + 6464.67 =14364.37 You forgot that the first 60 payments would still accumulate interest for the ...
*September 21, 2015*

**Math**

Just list them: Q D N 1 0 1 0 3 0 0 2 2 0 1 4 0 0 6
*September 21, 2015*

**Math**

prob(woman) = 80/300 = 2/75 prob(not woman) = 73/75 prob(1 women of 3) = C(3,1) (2/75)(73/75)^2 = appr .075790 prob(no woman) = (73/75)^3 = .922114
*September 21, 2015*

**Pre-calculus**

for your last part, you want -16t^2 + 96t > 96 let's see when -16t^2 + 96t = 96 t^2 - 6t +6 = 0 t = (6 ± √12)/2 = 3 ± √3 = 1.268 or 4.732 so between these two times the ball is above 96 ft so the ball is above 96 ft for 3.464 seconds
*September 21, 2015*

**Math**

milk : water = 5 : 1 = 5x : x 5x + x = 9 carry on
*September 21, 2015*

**Math**

#2 (1/2)(3/7) =3/14 ---- B The others are correct
*September 21, 2015*

**Math**

I don't see your answers How can I check them ?
*September 21, 2015*

**Algebra**

amount of the 20% stuff --- x L amount of the 70% stuff --- 25-x .2x + .7(25-x) = .4(25) how about multiplying each term by 10 2x + 7(25-x) = 4(25) 2x + 175 - 7x = 100 -5x = -75 x = 15 take over
*September 21, 2015*

**Algebra**

base distance --- x height where the ladder touches --- x+7 x^2 + (x+7)^2 = 13^2 2x^2 + 14x + 49 = 169 x^2 + 7x - 60 = 0 (x+12)(x-5) = 0 x = -12 , which makes no sense or x = 5 finish it up
*September 21, 2015*

**algebra**

total scores = 4(5) + 7(4) + 6(3) + 2(2) + 0 = 70 number of student = 20 Average score = 70/20= 3.5
*September 21, 2015*

**algebra**

first exposure = 98(5) dBhours 2nd exposure = 82(3) dBhours average exposure = (490+246)dBhours/8 hours = 92 dB this would make "mathematical" sense, I don't know if it works that way in reality
*September 21, 2015*

**How about mensuration ?**

Volume of cone = (1/3)π r^2 h volume of cylinder = π r^2 h , so three times as much so clearly the height of the cylinder is 4 cm
*September 21, 2015*

**math**

taxable items ---- x cost of taxable items = x + .06x = 1.06x non-taxable items ---- 25-1.06x .06x = .30 x=5 So he bought 5$ of taxable and 19.70$ of nontaxable items. check: 5 + .06(5) + 19.75 =
*September 21, 2015*

**math**

they are all correct
*September 21, 2015*

**Drawing**

Draw two perpendicular diameters. Mark where they intersect the circles, there should be 4 of those marks bisect each of the 90° angles and draw those diameters. Mark their intersection points on the circle. Join adjacent marks on your circles with line segments to get ...
*September 21, 2015*

**maths**

You have: 2x + 2y = 18 x+y = 9 or y = 9-x xy = 20 x(9-x) = 20 9x - x^2 - 20 = 0 x^2 - 9x + 20 = 0 solve for x, hint: it factors nicely
*September 21, 2015*

**math urgent**

Ahhh, you changed it LS = sin20/cos20 + 4sin20 = sin20/cos20 + 4sin20cos20/cos20 = (sin20 + 4sin20cos20)/cos20 = (sin 20 + 2sin40)/cos20 = (sin20 + 2sin(60-20))/cos20 = (sin20 + 2sin60cos20 - 2cos60sin20)/cos20 = (sin20 + √3 cos20 - sin20)/cos20 = √3cos20/cos20...
*September 21, 2015*

**math**

a rational number is defined as a/b , where a and b are integers, with b≠0 when you divide two integers you get exactly that form
*September 21, 2015*

**Math**

This type of question often comes up when you study "permutations" and "combinations" You clearly must be studying permutations and combinations In this case you are "choosing" any 2 of the 6 points choose ----> combinations, (the order in ...
*September 21, 2015*

**Math**

500!/21 times
*September 20, 2015*

**Math**

#2 is clearly d) #4 is clearly d) #5 -3 is an integer -3 = -3/1 so I can write it as a fraction What do you think?
*September 20, 2015*

**math for managers**

Why are you repeating this question? http://www.jiskha.com/display.cgi?id=1442769066
*September 20, 2015*

**algebra**

done, look back when you were Jaqueline
*September 20, 2015*

**algebra (check work)**

no |7-3-12} = |-8| = 8 you did |7| + |-3| + |-12| , which was not the question
*September 20, 2015*

**Math**

Other than the names and numbers, how does this question differ from http://www.jiskha.com/display.cgi?id=1442782042 Did you not follow my steps?
*September 20, 2015*

**College Algebra**

let the number of years be n 105 + n = 5(5+n) no recorded human has lived that long, I suspect a typo
*September 20, 2015*

**Math**

you can use the same website I gave you in a previous post to answer your last two questions this time use "area from a value" and enter the values in "between"
*September 20, 2015*

**Math**

go to http://davidmlane.com/hyperstat/z_table.html first click on "value from an area" enter 0.69 into "area" enter 55 as the mean enter 9 as the sd click on "between" to get: $45.86 and $64.147
*September 20, 2015*