Friday

September 30, 2016
Total # Posts: 36,087

**Math**

area of parallogram = base x heigh = 6.5(4.8) = .. new dimension: base = 13 height = 6.3 new area = 13(6.3) = .... take the difference

*May 17, 2016*

**Algebra**

y = kx plug in the given values of x and y, then solve for k rewrite the original equation, now that you know k

*May 17, 2016*

**math**

(1/2)(l) = 2/3 l = (2/3) ÷ (1/2)

*May 17, 2016*

**math**

(sum of 4 tests + x)/5 = 77

*May 17, 2016*

**Math3(Reiny Please Help)**

h(t) - -9.81t^2 + 0t + h = 0 when it hits the ground when t = 3.5 -9.81(3.5)^2 + h =0 h = 120.1758 m b) repeat for the equation h(t) = -9.81t^2 -5t + 120.1725 set that equal to 0 and solve for t , reject any negative values of t

*May 17, 2016*

**Math2(Reiny Please Help)**

set 0.02(3s^2 + 20s) = 50 3s^2 + 20s = 2500 3s^2 + 20s - 2500 = 0 Use the quadratic formula, reject the negative answer.

*May 17, 2016*

**Math(Reiny Please Help)**

let the width against the barn be x ft let the length parallel to the barn be y ft so total length = 600/15 = 40 so she needs to fence 40 ft 2x + y = 40 y = 40-2x area =xy = x(40-2x) = 40x - 2x^2 are you taking Calculus? if so, d(area)/dx = 40 - 4x = 0 for a max of area x = 10...

*May 17, 2016*

**Math**

a) number greater than 9: 10,11,12,13,14,15 so 6 of them prob(as stated) = 9/15 = 3/5 b) do it the same way, count how many are prime, and how many are composite

*May 17, 2016*

**Math**

areas of similar figures are proportional to the square of their corresponding sides so the larger one is 9 times as large, or 243 m^2 or, if you didn't know that property let the original be (1/2)(base)(height) = 27 new one is (1/2) (3base)(3height) = 9 (1/2)(base)(height...

*May 17, 2016*

**MATH**

of course! you must have the same units 12/9 would be a meaningless calculation. 36 ft ÷ (9/12) ft = 48 Now, the question is not clear about posts at the end. e.g. If the fence has one side along a house, would you need a post right against the house at each end? If so ...

*May 17, 2016*

**math**

term5 = a+4d term2 = a+d a+4d = 2(a+d) a+4d = 2a + 2d a = 2d sum(20) = 10(2a + 19d) = 1150 2a + 19d = 115 4d+19d=115 23d = 115 d = 5 a = 10 you MUST know how to do this simple kind of question. Repeat the solution on your own, without looking at mine. Practise, practise, ...

*May 17, 2016*

**math**

volume of well = π r^2 h = π(7^2)(20) = 98π m^3 surface area to be covered by dirt = 100(42) - π(7^2) =4200 - 49π m^2 let the depth of the dirt be h m (4200 - 49π)h = 98π check and do my arithmetic

*May 17, 2016*

**Math**

What is your choice ?

*May 17, 2016*

**Math**

If expressed in terms of y ... 4y = 2x y = (2/4)x = (1/2)x so yes, with k = 1/2

*May 17, 2016*

**Math/algebra**

- find the mean - take the difference between each of your data values and the mean - square each of these differences - add up these squares of differences - divide by 10 - take the square root I will not do the arithmetic of that for you

*May 17, 2016*

**Math/algebra**

you have a GP, with a = -2, r = -2 term(20) = a r^19 = -2(-2)^19 = (-2)^20 = 2^20 = 1,048,576

*May 17, 2016*

**Math Help Please I Don't Understand**

you have to be familiar with the meaning of the constants in an equation such as y = a sin k(Ø+d) + c a is the amplitude, our range of heights is 60 ft so a = 30 y = 30sin kt + c , where t is in minutes the lowest value so far would be -30, but we need our lowest to be...

*May 17, 2016*

**Geometry**

So you want them to be an arithmetic sequence 19 , 19+d, 19+2d, 19+3d but 19+3d = 55 3d= 36 d = 12 etc

*May 17, 2016*

**MATH**

Let the width be w area of first = 12w area of 2nd = 8w 12w - 8w = 320 carry on

*May 17, 2016*

**math**

I noticed that Steve answered this for you 20 minutes ago. Why are you repeating it ?

*May 17, 2016*

**Algebra**

The way you typed it, it would be undefined for x = 0 if you meant: (x+1)(x-2)/(x^2-25) then it would be undefined for x = ± 5

*May 16, 2016*

**Algebra**

so your height formula is h = -4.9t^2 + 4.9t + 0 , assuming kicked from ground when it lands, h = 0 -4.9t^2 + 4.9t = 0 -4.9t(t - 1) = 0 t = 0 ----> at the moment the ball is kicked or t = 1, it lands 1 second later

*May 16, 2016*

**Finance**

This is a normal amount of annuity problem payment = 650 i = .078/4 = .0195 n = 4(5) = 20 amount = 650 ( 1.0195^20 - 1)/.0195 = $15,714.90

*May 16, 2016*

**math**

you will be in the 4th quadrant, 39° down from the x-axis cos 39° = x/800 x = 800cos39 = 621.7 m east y = 800sin39 = 503.5 m south notice : 621.7^2 + 503.5^2 = 639979.1489 √639979.1489 = 799.987 , not bad

*May 16, 2016*

**Math**

y^2 + 9y + 9 = 0 straightforward quadratic equation, unfortunately it does not factor, so .... by the formula y = (-9 ± √45)/2

*May 16, 2016*

**Math(Reiny Could You Help?)**

the vertex of f(x) is (2,9) The vertex of g(x) is to the right 2 units and 5 units down, so its vertex must be (4,4) since the "shape" has to be the same, we need the same 3 in front so g(x) = 3(x-4)^2 + 4 domain: the set of real numbers range: y ≥ 4 , since ...

*May 16, 2016*

**Math**

golf balls ---- 20x tennis balls -- 5x 20x+5x = 100 25x = 100 x = 4 so 80 golf balls and 20 tennis balls

*May 16, 2016*

**Geometry**

slope of AB = (4+8)/(-9+7) = 12/-2 = -6 so the slope of the perpendicular = 1/6 midpoint of AB = (-8,-2) equation of our line: y + 2 = (1/6)(x+8) 6y + 12 = x+8 x - 6y = 4

*May 16, 2016*

**math**

We clearly need a diagram to know what you are talking about. Since we cannot post diagrams here, ......

*May 16, 2016*

**Math**

your function is modelled by a parabola which opens downwards. when the package reaches the water, h(t) = 0 -4.9t^2 + 10t + 1200 = 0 t = (-10 ± √23620)/-9.8 = -14.662 or 16.7029 We will reject the negative time, so it took appr 16.7 seconds for the package to ...

*May 16, 2016*

**Math (Trig)**

you know that the point is in quad II and tanØ = 2/-1 I know that for tanØ= +2, Ø = appr 1.107 so our angle in II is Ø = π-1.107 = 2.0344 so it has to be (5, 2.0344) if you use the form (r,Ø)

*May 16, 2016*

**Math**

I don't like the wording "repeatedly" Usually this type of question uses "continuously" to describe the increase. amount = a e^(kt) , where k is the annual rate , t is the time in years and a is the initial amount. e^(k(9.25)) = 2 take ln of both sides ...

*May 16, 2016*

**math**

A not-so-subtle way to promote two wineries??

*May 16, 2016*

**Calculus**

We need their intersection: 2x^2 - 2 = x^2 + 1 x^2 = 3 x = ± √3 we want only the part in the first quadrant effective height = x^2 + 1 - (2x^2 - 2) = 3 - x^2 area = ∫(3 - x^2) dx from 0 to √3 = [3x - (1/3)x^3] from 0 to √3 = 3√3 - (1/3)(3&#...

*May 16, 2016*

**Math**

h(t) = -4sin (π/4)(t-1)+2.5 The period of this function is 2π/(π/4) = 8 So we want to see where the sine curve falls below the x-axis for 3 periods of the curve, starting at t=0 0 = -4sin (π/4)(t-1)+2.5 4sin (π/4)(t-1) = 2.5 sin (π/4)(t-1) = .625 ...

*May 16, 2016*

**math**

f+k = 1548 f+j = 1842 subtract those two equations: j-k = 294 j = 294 + k k/j = 4/7 4j = 7k j = 7k/4 sub into j = 294+k 7k/4 = 294 + k times 4 7k = 1176 + 4k 3k=1176 k = 392 then j = (7/4)(392) = 686 f+j = 1842 f = 1156

*May 16, 2016*

**math**

227.5( 1- (1+i)^-60)/i = 9500 You will need some "fancy" methods to solve this type of an equation, e.g. Newton's Method I just ran it through Wolfram and got i = .0127495 for a monthly rate or an annual rate of appr . .152994 or appr 15.3% per annum compounded ...

*May 16, 2016*

**Statistics**

I assumed you know how to find the mean and sd for the given information.

*May 15, 2016*

**Statistics**

straightforward .... find z scores for both 12 and 14 minutes go to the chart, look up the two z-scores proabilities, then subtract them

*May 15, 2016*

**Math Help**

The two questions are very similar in setup, I will do the first one, you do the second length = integral √( 1 + (y')^2) dx from a to b yours: y = (2/3)x^(3/2) + 2 y' = x^(1/2) (y')^2= x length = integral √( 1 + x) dx from 14 to 16 = [ (2/3)(1+x)^(3/2...

*May 15, 2016*

**Math**

5x - 3 = 7x + 11 x=-4 <------------ No 5x-7x = 11+3 -2x = 14 x = -7 3w -4 = w+8 w =6 < --------- Yes

*May 15, 2016*

**Algebra**

Just add the "like" terms

*May 15, 2016*

**Math**

times 3 , the LCD b-4 = 3 take over

*May 15, 2016*

**Integral calculus**

We are rotating a circle with centre at (3,0) and radius 3 around the y-axis Because of symmetry we can use the part only above the x-axis, then double it. see Khan for a nice explanation of the shell method https://www.khanacademy.org/math/integral-calculus/solid-revolution-...

*May 15, 2016*

**Percent**

what is 46/1.15 ?

*May 15, 2016*

**Math**

15,590(1.05)^n = 55,433 , where n is the number of years 1.05^n = 3.55567.. (I stored it in memory) take logs of both sides nlog 1.05 = log 3.55567.. n = 26.00002.. I would say she owned it 26 years

*May 15, 2016*

**Algebra**

What's with the 8_/8 ?? We solve equations, I don't see an equation. If you are evaluating (3/8)(2/6) = 6/48 = 1/8

*May 15, 2016*

**math**

r = 17y so area = π(17y)^2 = 289y^2 π

*May 15, 2016*

**algebra/trigonometry**

Didn't that answer strike you as totally unreasonable? How can the kite-string be only 1 cm long ?? Steve told you : 75/x = sin 60° so x sin60 = 75 x = 75/sin60 = appr 86.6 metres

*May 15, 2016*

**Math**

Final bill = $97.38(.65)(1.18) = $74.69 share of each friend = 74.69/4 = $18.67

*May 15, 2016*

**Maths**

Come on folks, this is silly. 4:37 + 2:48 = 277 minutes + 168 minutes = 445 minutes = 7 hours and 25 minutes or 7:25 If you have a scientific calculator, look for a key like D°M'S Use it for either adding/subtracting time or angles in degrees. enter 4 D°M'S 37...

*May 15, 2016*

**math**

all 4 angles have to add up to 360°, so x + x+10 + x+20 + x+30 = 360 solve for x, then sub into the angle expressions

*May 15, 2016*

**math (PLZ HELP ASAP)**

teacher's age --- x son's age ---- y x-2 = 3y x = 3y+2 x-7 = 2(y+2) 3y + 2 - 7 = 2y + 4 y = 9 x= 3(9)+2 = 29

*May 14, 2016*

**math**

Assuming you meant: 480 - 8t - .8t^2 or R1 sub in all the values of t into R1, then add them up sub in all the values of t into R2, then add them up compare the two answers.

*May 14, 2016*

**math**

"that no one even out of the 4 balls being white" ?? you mean, none of the balls drawn is white ? 8 of the 12 are "non-white" prob(of your event) = (8/12)(7/11)(6/10)(5/9) = 14/99 assuming the balls are not returned after they are drawn

*May 14, 2016*

**Maths fractions**

Let c be the capacity of the tank (1/5)x + 700 = (2/3)x times 15, the LCD 3x + 10500 =10x 7x=10500 x = 1500 The tank holds 1500 ml or 1.5 L

*May 14, 2016*

**Functions Math**

After 3 hours of driving, there are 10 gallons left.

*May 14, 2016*

**Math**

amount = 3000(2)^(t/2) , where t is the number of days = 3000(2)^(15/2) = 543,058 How did you get 45,000 ?

*May 14, 2016*

**Algebra**

1+1.1p - (1.5p - 1) = 4 1 + 1.1p - 1.5p + 1 = 4 -.4p = 2 p = - 5 check: 1.5(-5) - 1 = -8.8 1+1.1(-5) = -4.5 their difference is 4

*May 14, 2016*

**Algebra**

really the same question as this one: http://www.jiskha.com/display.cgi?id=1463240595 Just change the numbers

*May 14, 2016*

**Math**

3(5x+5) - 2 = 0 15x + 15 - 2 = 0 15x = -13 x = -13/15 check: g(-13/15) = 5(-13/15) + 5 = 2/3 f(2/3) = 3(2/3) - 2 = 2-2 = 0 my answer is correct

*May 14, 2016*

**math**

266 2/3% = 800/3 % = 800/300 = 8/3 so (8/3)x = .6 x = 1.8/8 = .225

*May 14, 2016*

**Algebra**

#1, ok #2, y varies inversely with x ---> y = k/x given: if y=2, x=8 2 = k/8 k = 16 so y = 16/x <------- D

*May 13, 2016*

**Geometry**

let the slant height be s s^2 = 8^2 + 37^2 s = 37.8549.. Lateral surface area = πrs = π(8)(37.8549..) = appr 9514 , none of the given choices if we include the circular base of 201.062 we get appr 1152 m^2

*May 13, 2016*

**Math**

This question was answered here, why are you repeating it ? http://www.jiskha.com/display.cgi?id=1463122066

*May 13, 2016*

**Math**

Why did you switch names? http://www.jiskha.com/display.cgi?id=1463155297

*May 13, 2016*

**Math**

I suspect you are missing a term and it should be like this. (or else not much will cancel) [(x^2 + 2x + 1)/(x^2 - 8x + 16) ] / [(x+1)/(x62-16) ] = [(x+1)(x+1)/(x-4)(x-4)) ]/[ (x+1)/(x-4)(x+4) ] = (x+1)(x+1)/(x-4)(x-4)) * (x-4)(x+4)/(x+1) = (x+1)(x+4)/(x-4)

*May 13, 2016*

**Math**

look at Steve' solution to the same question: http://www.jiskha.com/display.cgi?id=1367836044

*May 13, 2016*

**maths**

I don't see your choice of answer? Did you forget it?

*May 13, 2016*

**Algebra**

Your time of 3.75 seconds is correct. Now sub that into the original equation for h I certainly did not get 7.58

*May 13, 2016*

**geometry**

excuse me, but I spent considerable time doing this for you yesterday http://www.jiskha.com/display.cgi?id=1463065994 Why are you posting it the same way without altering any of the parts I questioned? What part of my answers did you not like ?

*May 13, 2016*

**math**

#1, #2 are correct #3 - #9 need a look at the diagrams, which of course we can't post here #10 - #12 look good #13 ----- need diagram, can't tell which numbers go where #14 --- need diagram #15 , I guessed what you meant, looks ok #16 18/15 = x/5 15x = 90 x = 6 #17 ...

*May 12, 2016*

**Math/Precal**

According to your wording, a digit cannot be used more than once. I stand by my answer .

*May 12, 2016*

**Math/Precal**

the first digit has to be either a 4,5,6, or 7 number of cases = 4 x 9 x 8 x 7 = 2016

*May 12, 2016*

**Math**

you want 2 from the 5 boys, and 3 from the 6 girsl number of selections = C(5,2) x C(6,3) = .......

*May 12, 2016*

**Math**

Is this a follow up from your previous question? term(3) = ar^2 = 20 a = 20/r^2 a/(1-r) = 3a 1/(1-r) = 3 same as in your previous post, r = 2/3 then a = 20/(4/9( = 20(9/4) = 45 test: your sequence is 45 , 30 , 20 , 40/3 , 80/9 , ... is the third term 20 ? , YES sum of all ...

*May 12, 2016*

**Math**

a/(1-r) = 3a divide by a 1/(1-r) = 3 1 = 3 - 3r 3r = 2 r = 2/3 plug in r = 2/3 a/(1 - 2/3) = 3a a/(1/3) = 3a 3a = 3a , which is a true statement, so "a" can be anything. But in a GP, the first term cannot be zero so the first term can be any real number except zero.

*May 12, 2016*

**Algebra 1**

"in the idea has law" ???? P = k/V if P=30, V = 150 30 = k/150 k= 4500 then P = 4500/V so when V = 50 P = 4500/50 = 90 The pressure is 90 p.s.i.

*May 12, 2016*

**math**

It is assumed that all questions are posted in English.

*May 12, 2016*

**Algebra**

looks like Steve gave you some important advice on this type of question yesterday. http://www.jiskha.com/display.cgi?id=1462996317 You apparently chose to ignore his suggestion, and posted this question exactly the same way

*May 12, 2016*

**Algebra**

the way you typed it: x/7x+x^2 = (1/7)x^2 + x^2 = (8/7)x^2 -----> none of the choices if you meant: x/(7x)+x^2 = 1/7 + x^2 -----> none of the choices If you meant: x/(7x+x^2) = x/(x(7+x)) = 1/(7+x) , x ≠ 0 -----> none of the choices one of the choices could fit ...

*May 12, 2016*

**maths**

variance of 49 minutes ----> SD = 7 find the z-score for 45 minutes, 60 minute, 75 min and 90 min , as you will need them notice the z-score for 45 minutes = (45-68)/7 = -3.2857 most tables or charts will give you results for z-scores between -2.99 and +2.99 values outside ...

*May 11, 2016*

**math**

let the amount drained be x gallons These x gallons will contain .4x gallons of antifreeze amount left of the old stuff = 5-x gallons so .... .15(5-x) + (1)x = .4(5) solve for x Let me know what you got, so I can check your answer.

*May 11, 2016*

**math**

correct!!

*May 11, 2016*

**math**

ummmhh, find the area of each circle, then subtract the smaller from the larger.

*May 11, 2016*

**maths**

Make sure the points given are listed as consecutive points of the figure, either clockwise or counterclockwise. They are. list them in a column, starting with any point, I will start with A 3 3 -2 5 -1 2 1 1 3 3 , you repeat the first one you started with Area = | (1/2)(...

*May 11, 2016*

**math**

(h/2)(b1+b2)=33.6 2(b1+b2) = 33.6 b1 + b2 = 16.8

*May 11, 2016*

**algebra word problem**

Total gas used for the trip = 12.857 gallons rate for the whole trip = 27 mpg so distance of trip = 27(12.857) miles = 347.139 miles let the number of gallons used at the 19 mpg rate be x then the number of gallons used at the 34 mpg rate be 12.857 - x 19x + 34(12.857 - x) = ...

*May 11, 2016*

**math (PLZ HELP ASAP)**

simpler setup: Julia's age --- x Wendy's age --2x Father's age -- 10x In 4 years from now: Wendy --- x+4 Father --- 10x + 4 10x+4 = 6(x+4) 10x+4 = 6x+24 4x=20 x = 5 Father: 10x = 50

*May 11, 2016*

**Math**

I would expand it first ... (-1/2)x + 10 + (2/3)x = 20 the LCD is 6, so multiply each term by 6 -3x + 60 + 4x = 120 now it is easy ....

*May 11, 2016*

**Math algebra**

evaluate 4x^2(2x+x^3y)+x^y for x = 5 and y=0 4x^2(2x+x^3y)+x^y = 4(5^2)(10 + 5^0) + 5^0 = 100( 10 + 1) + 1 , .............. anything^0 = 1 = 1100

*May 11, 2016*

**math**

Silas has a valid claim

*May 11, 2016*

**maths**

prob (odd on a single toss) = 3/6 = 1/2 prob(not odd) = 1/2 prob that of 6 tosses, exactly 4 will show an odd = C(6,4) (1/2)^4 (1/2)^2 = 15(1/2)^6 = 15/64

*May 11, 2016*

**small correction - maths**

bob is right, mrfrank has an extra 3 hanging around should be (9/2)(1+tan (3x))^(1/2) (sec^2 (3x) )

*May 11, 2016*

**math**

amount = 722 (1/2)^(t/71) , where t is in hours so after 17 hours .... amount = 722(1/2)^(17/71) = 722(.847076...) = 611.589 -------------> choice B = appr 612 kg It would be more logical to use t as a variable for time instead of x, but hehh, whatever turns them on.

*May 11, 2016*

**Needs Clarification ----Calculus**

The curve is "bell-shaped" http://www.wolframalpha.com/input/?i=plot+y+%3De%5E(-x%5E2) Let the point of contact in quad I be P(x,y) Did you mean "largest triangle" ?? If you want the "largest rectangle" then the tangent line is not needed.

*May 11, 2016*

**my error - maths**

forget about my solution, I saw that as a = 2 instead of a = .2 so s = .1 t^2 + 2t at t = 10 s = .1(100) + 2(10) = 30 m

*May 11, 2016*

**maths**

How did you get 100.2 ?? a = 2 v = at+c = 2t + c when t = 0, v = 2 2 = 0 + c v = 2t + 2 s = t^2 + 2t + k when t=0 , s = 0 , thus k = 0 s = t^2 + 2t when t = 10 s = 10^2 + 2(10) = 120

*May 11, 2016*

**mathematics**

I am sure collins meant to say tan 61° = h/53 , just a typo

*May 11, 2016*

**12th Grade**

(5x^2-5x-10)√(x+7) + (2x+6)√(x+2) ≥ x^3+13x^2-6x-28 , where x ≥ -2 A quick mental inspection shows that when x = 2, the roots become exact. Could it be ? could it be? testing for x = 2 LS = (20-10-10)√9 + (4+6)√4 = 0 + 20 = 20 RS = 8 + 4(13...

*May 10, 2016*