Friday

April 18, 2014

April 18, 2014

Total # Posts: 21,739

**Math**

well, just evaluate 15*14*13 / 1*2*3

**engineering mathematics 1**

you have 2x+y=80 and you want the maximum area, a = xy = x(80-2x) find the vertex of that parabola for max area. You will find that the fence is equally distributed among the lengths and widths. That is, 2x = 40 y = 40 so the max area pen is 20x40

**math**

the quotient is always less than the dividend

**Math**

subtract and you have 7y = -14 y = -2 now plug that into either equation to find x = -3

**Math**

working all those words into numbers, we have maximize m+r subject to 10m + 15r <= 500 25m + 15r <= 600 I see that we have 15m <= 100 so m <= 6 Given that, if we choose only 1 mouse, we have 15r <= 490 15r <= 575 so, r <= 32 max achieved at 6 mice and 29 r...

**Algebra**

If using x lbs of 4% milk, .04x + .30(200-x) = .08(200)

**math**

what, you have no idea how to list multiples of 4? How about I illustrate with multiples of 3? 3,6,9,...

**Math**

the value of the coffee in each part must add up to the whole. So, 7.50x + 9.50(12-x) = 8.00(12) x = 9 so, 9 lbs at $7.50 and 3 lbs at $9.50

**Algebra**

cross multiply to clear the fractions and you have (x+12)(x+8) = x(x+4) x^2+20x+96 = x^2+4x 16x = -96 x = -6

**:-)**

Yeah, I sometimes have to step back and ask myself what it would take for the problem to make sense. It's not always possible to come up with an answer, either!

**Math 4**

It lowered the temp by 27°, not to. 19 - 27 = -8

**Math 3**

From the context, I gather the day temp is 107° and the night temp is -153°. 107 - (-153) = 310° warmer by day than by night.

**Math 2**

or, more generally, 124 - (-21) = ? If a < b, the difference between a and b is b-a.

**Math 221**

The given line has slope -3 So, the parallel line also has that slope. Now you have a point and a line, so the equation is y-5 = -3(x+1) y = -3x+2 Your first line was okay, but then you started dropping x's along the way. x1 = -1, not 1.

**math**

yes, it's 1/5 for each marble. So, the chance of getting BOTH greens is 1/5 * 1/5 = 1/25

**math**

2 greens out of 10 marbles, so: (B)

**math**

(60-25.5)/2 = 17.25

**Calc**

same as last time, only use the quotient rule: g = 5x/f, so g' = (5f-5x*f')/f^2 g'(3) = (5*4-15*3)/4^2 = -25/16

**Calculus**

g' = 8f + 8x * f' g'(3) = 8f(3) + 24*f'(3) = 8*4 + 24*5 = 152

**Math**

Did you try using h(t) = -16t^2 + 128t ???

**Math**

(a) correct. (b) correct (c) correct (d) max height is at t=4. But the question was, what is that height? h(4) = 256 No idea how to graph it with your calculator. The graph can be seen at http://www.wolframalpha.com/input/?i=-16t^2%2B128t

**Algebra**

If he intended to buy x dozen, the price was evidently 210/x cents/dozen. Instead, (x-1/2)(210/x + 3) = 209 x = 6 So, the price per dozen was expected to be $.35 Instead, he wound up paying $.38/doz, meaning he bought 5 1/2 dozen, which cost $2.09

**Physics**

(1500cm^3)/(1.0s) / (pi*(.49/2)^2 cm^2) = 7954 cm/s or 7.9 m/s not sure on B.

**Math (2 Questions) - Please Help**

F+V-E = 2 If you count all the vertices of each polygon, each vertex is counted twice. So, 12+20 + (5*12+6*20)/2 - E = 2 E = 120 draw a diagram. If you draw horizontal and vertical lines through the point and through the center of the circle, you will see that (r-25)^2 + (r-18...

**Algebra**

the function is undefined when you try to divide by zero. So, if b+4=0, the function is undefined.

**Math- urgent**

the obvious one is -265:100 also 53 : -20

**gg**

that would be 125000(.27) = $33,750

**Math**

solve for t in 6 + 31t - 16t^2 = 4 t = 2

**Trig**

use law of cosines. 70^2 = 65^2 + 90^2 - 2(65)(90)cosθ

**college math**

Sounds like they are repeatedly doing surveys. In most of the surveys (19/20), they sample enough of the population to be confident that their results are within 3.2% of the true percentage.

**CALCULUS**

with a slight change to the numbers, this question is treated at http://www.jiskha.com/display.cgi?id=1392927547

**Algebra**

not sure what you want to do. If you just want to do long division, visit calc101.com and click on the "long division" button. Enter your polynomials and see all the details.

**5TH GRADE MATH**

If you mean that the sum of the three perimeters is 140 yards, then you can divide 140 up any way you like. If you pick, say, 30,50,60 yards as your three perimeters, then you can divide the values up as you will. For example perimeter 30: 7x8 yards perimeter 50: 25 ft by 50 f...

**Mathematics**

P is in QI, so if cosP = 5/13, tanP=12/5 Q is in QIII, so if tanQ = 8/15, sinQ = -8/17 17tanPsinQ = 17(12/5)(-8/17) = -96/5

**trigonometry**

h/63 = sin 45

**calculus help**

There's a nice discussion here: http://math.stackexchange.com/questions/126755/lhospitals-rule-with-indeterminate-powers

**Math**

to figure a percentage, just divide and multiply by 100. 2023.60/55953.77 = 0.0361 = 3.61%

**Calculus Help!!!!!**

should be no problem. That's just Algebra II. Anyway, y = x^3/(x+1)^2 y' = x^2(x+3)/(x+1)^3 y" = 6x/(x+1)^4 see the graph and some analysis here: http://www.wolframalpha.com/input/?i=x^3%2F%28x%2B1%29^2

**Precalculus**

You have (tan+sec-1)/(tan-(sec-1)) multiply top and bottom by tan+sec-1 and you have (tan+sec-1)^2/(tan^2-(sec-1)^2) tan^2+sec^2+1+2tan*sec-2tan-2sec)/(tan^2-sec^2+2sec-1) (sec^2+tan*sec-tan-sec)/(sec-1) (tan+sec)(sec-1)/(sec-1) tan+sec

**Calculus Help Please!!!**

As mentioned, let BC = x distance over water: √(x^2+49) distance over land: 11-x (a) energy expended: y = 1.3√(x^2+49) + 11-x dy/dx = 1.3x/√(x^2+49) - 1 y'=0 at x = 70/√69 what do you get for the other parts?

**algebra**

you just have a right triangle with legs 5 and 8. So, the rope, forming the hypotenuse is √(25+64) = √89

**Calc 2**

and the (-2/3)^k part is just a geometric series S = (-2/3)/(1+2/3) = -2/5

**geometry**

x^2 + 6371^2 = (6371+353)^2 x = 2150

**Algebra**

2 hours

**Math**

√(25^2 + 10^2)

**math**

(P2-P1)/P1 * 100

**Calc**

dQ/dt = kQ (if you please)

**CHEM**

since PV/T is constant, if P is held constant, then V/T is constant. if T is increased by a factor of 296/90, then V is increased by a factor of 296/90. So, multiply 3.3 by that factor.

**math (Matrix algebra)**

Enter your data at http://www.gregthatcher.com/Mathematics/GaussJordan.aspx to see all the details

**math (Matrix algebra)**

assuming you mean a determinant, and calling your matrix M, I get |M| = 31-3x So, if 31-3x = 25, x=2 The inverse can be seen at http://www.wolframalpha.com/input/?i=inverse+{{-2%2C+1%2C+x%2B2}%2C{3%2C+x-4%2C+5}%2C{0%2C+1%2C+3}}+ substitute in x=2 if you just want the numbers.

**maths**

since one line is slanting, and the other is horizontal, I'd say they are not parallel. Even is there's an x missing from the 2nd line, it will still not be parallel.

**maths**

x y -4 13/2 -3 5 -2 7/2 ...

**Algebra**

since time = distance/speed, we have 5/x + 5/(2x) = 15/(2x)

**Math**

5% growth is just 1200000*1.05^n after n years for #c, we have 1200000*(1.05)^7*(0.92)^8 = 866,581

**Algebra**

x^2+8x+15 = (x+3)(x+5) so, you have (x+3)(x+5)/(x-4) * (x-4)(x+4)/2(x+3) the x+3 and x-4 cancel, leaving (x+5)(x+4)/2

**math**

out of 36 possible rolls, only 4 have the sum < 5: 12 13 21 22 What's the chance of no 6's? 5/6 * 5/6 so, take 1-P(~6,~6) = 11/36

**Algebra**

the point of Reiny's question is to remind you that division by zero is undefined. So, when b+4=0, the expression cannot be evaluated. That is, when b = -4, the expression is undefined.

**Math**

I get zero. ∫[-1,2] 1-x^2 dx = x - x^3/3 [-1,2] = (2 - 8/3) - (-1 + 1/3) = 0 yeah, I know, we have to divide by 3 ...

**Trig - heh**

now, just change all those 225's to 255's and redo the calculations.

**Math**

PR/QR = sin(Q) PR/120 = sin(10.5)

**Calculus Help Please Urgent!!!**

1/3 pi r^2 h = 30, so h = 90/(pi r^2) surface area = 2 pi r s where r^2+h^2 = s^2, so a = 2 pi r √(r^2 + (90/(pi r^2))^2) = 2/r √(pi^2 r^6 + 8100) for minimum paper, we need da/dr = 0, so, as wolframalpha so ably shows at http://www.wolframalpha.com/input/?i=2+pi+r...

**mathematics for management**

5^x 25^2y = 1 5^x 5^4y = 1 5^(x+4y) = 1 x+4y = 0 3^5x 9^y = 1/9 3^5x 2^2y = 3^-2 5x+2y = -2 x = -4/9 y = 1/9

**math**

Assuming you mean (8^y)^y, we have 8^y^2 = 2^3y^2 1/32^y = 2^-5y 4 = 2^2 3y^2-5y = 2 y = 2 or -1/3

**mathematics for management**

2log(a+b) = log (a+b)^2 = log (a^2+2ab+b^2) 2log a + log(1 + 2b/a + b^2/a^2) = log (a^2 (a^2+2ab+b^2)/a^2) looks the same to me

**math**

Assuming a 360-day year, 8000 * .095 * 1/3 = 253.33

**math**

ignoring all those trailing zeros, 58/6 = 9.67

**calculus**

1/10 ∫[0,10] 3/(x+1) dx = 3/10 ln(11)

**math**

the bisector BD and half the chord CD form a right triangle with the radius BC BC^2 = 3^2+5^2

**math**

the one with an x term, but no higher powers.

**calculus**

So, the height is 40/x^2 c(x) = 2x^2*5 + 4x(40/x^2)*2 = 10x^2 + 320/x set the derivative to zero, and you find minimum cost at x = 2∛2

**Precalculus**

for #2c, there is a second point at about (-1.38,3) see the graph at http://www.wolframalpha.com/input/?i=solve+5x^3-3x^5%2B1+%3D+3

**cal**

false. These are formulas for interest compounded k times per year.

**math**

have you tried your calculator?

**Math**

850000(1+.06/4)^(4*3.5)/4.75 = 220,419 850000(1+.06/4)^(4*5)/5.10 = 224,476

**statistics**

well, who has a negative z score?

**Math**

As I showed you earlier, it is ∫[0,8] 7/(x+1) dx ---------------------- (8-0) = 1/8 (7log(x+1) [0,8]) = 7/8 (log9-log1) = 7/8 log9 what were your solution steps?

**Algebra**

(r+2)/(r+4) - 3/(r+1) = (r^2-10)/(r^2+5r+4)

**math**

5n + 25q = 325 q = n-5 now just plug in q and solve for n.

**Algebra**

1/(g+2) + 3/(g+1) = (4g+7)/(g^2+3g+2)

**Math**

using FOIL, you get (2n)(6n) + (2n)(1) + (2)(6n) + (2)(1) = 12n^2 + 2n + 12n + 2 = 12n^2 + 14n + 2

**math trigonometry**

the law of cosines says 68^2 = 53^2 + 71^2 - 2*53*72 cosθ so, cosθ = (68^2-53^2-71^2)/(-2*53*72) = 0.42269 θ = 65°

**Algebra**

the common denominator is 2b, so you have 1/2b + b^2/2b = (1+b^2)/2b

**Math**

and there's your answer.

**Math**

17 is 17*1 so, what is 17*23.125?

**Mean, Median and Mode HELP!**

sort the data to get 4 6 7 9 10 11 11 12 15 16 Now it is easy to see mode = 11 median = 10.5 mean = 10.1

**Math**

distance is ∫[0,8] 3t√(640t^2) dt = 512

**Math**

that would be ∫[0,3] 300t^2/(t^3+32) + 5 dt let u = t^3 + 32 du = 3t^2 dt and now you have ∫[32,59] 100/u du + ∫[0,3] 5 dt = 15 + 100log(59/32)

**Math**

∫[-1,2] 1-x^2 dx ----------------------- (2-(-1))

**Math**

∫[0,8] 7/(x+1) dx ---------------------- (8-0)

**Math**

that would be (∫[0,8] 5e^-x dx)/(8-0) = 5/8 (1-e^-8)

**Algebra**

since the denominators are equal, just subtract the numerators: ((5x-2)-(x-2))/(4x) = (4x)/(4x) = 1

**trying to understand math**

in March, total sales were 9.00 * 125 * 31 = 34875.00 In April, (assuming 30 days, 15 days per half-month) 1st half: 9.00*125 * 15 = 16875.00 2nd half: 11.00*125 * 15 = 20625.00 total: 37500 avg at 11.50 = 43125 so she falls 5625 short. Two items need clarification... There...

**math**

(pi * .8^2 * .5 m^3) ----------------------- = 32 s (pi * .1^2 * 1 m^3/s)

**Algebra**

just solve your equation: x^2-81 = 115 x^2 = 196 x = 14 so, the base is 14+9 = 23 height is 14-9 = 5

**Algebra**

√(5x^2)+7x+2-√(4x^2+7x+18) = x-4 √(5x^2)-√(4x^2+7x+18) = -6x-2 now square both sides to get (5x-2) - 2√(5x^2)(4x^2+7x+18) + (4x^2+7x+18) = (6x+2)^2 4x^2+12x+16 - 2√(20x^4+35x^3+90x^2) = 36x^2 + 24x + 4 √(20x^4+35x^3+90x^2) = -16x^2-6x+...

**algebra 1**

both correct However, I'd have written #2d as (5x+2 + 3x-1)/2 just to show it's the average of two numbers, rather than half of each.

**algebra1**

looks like A to me

**College Cal 1**

if the 2-strand dimension is x, then we have f(x) = 2x + x + 2(15000/x) df/dx = 3 - 30000/x^2 min fence when df/dx = 0, at x = 100 so, the field is 100x150 as usual, the fencing is divided equally among the dimensions. ** f(x) = fencing(x) !

**alg**

since f(1) = 5, f-1(5) = 1

Pages: **1** | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>