Tuesday

November 24, 2015
Total # Posts: 35,768

**math**

well, she clearly can make 14/7 = 2 candles per box of wax. That help?
*October 1, 2015*

**@Reiny - Spoiler Alert**

Dang it, buddy, you're taking all the mystery out of math!
*October 1, 2015*

**Sphere find x**

if the diameter scales by a factor of x, the volume grows by x^3. So, if d -> 1.2d v -> 1.2^3 v = 1.728v That is, it grows by 72.8%
*October 1, 2015*

**Math 71x**

I assume plan B is a flat $30/month. If so, the costs are equal for x minutes if 20+0.04(x-200) = 30 And the question is poorly worded.
*October 1, 2015*

**math**

no clue. If all you have are inputs, how do you expect to find a rule? I expect you have not posted the problem as it was asked.
*October 1, 2015*

**Math**

assuming that the area is divided into three 25x40 areas, then the fencing needed is 2*75 + 4*40 If you want three 75 x 40/3 areas, that's different.
*October 1, 2015*

**trigonometry**

Just in case that wasn't enough of a hint, draw your diagram and notice that streetwidth = 30 cot15° - 30cot50°
*September 30, 2015*

**trigonometry**

use the cot function.
*September 30, 2015*

**Science**

How do binomial or 2 part names compare with early versions of scientific names? shorter longer descriptive in English my answer is descriptive
*September 30, 2015*

**math**

ah- much better. We need 4/5 B + 4/5 = B 4/5 = 1/5 B B = 4 Check: On Box A's side, we have 4/5 * 4 + 4/5 = 16/5 + 4/5 = 20/5 = 4
*September 30, 2015*

**Math**

no idea. what does b have to do with a scale balanced by box a and a 4/5 lb weight?
*September 30, 2015*

**math**

what's with all these expanding polynomials? That gives no extra insight whatever g = 1/(x^2+1) g' = -2x/(x^2+1)^2 g" = 2(3x^2-1)/(x^2+1)^3 since x^2+1 is always positive, g" is negative where 3x^2-1 < 0 x^2 < 1/3 That is on the interval (-1/√3,1...
*September 30, 2015*

**Permutations**

clearly, that is 10! = 3628800 Although, if all you care about is win, place, show then there are only 10!/7! = 720 ways to finish in the first 3 places.
*September 30, 2015*

**Math**

consider the total points. The total so far is 326. If the last grade is x, then you need 350 <= 326+x < 400 24 <= x < 74 If the 5th test counts as two, then it's like having six scores: 420 <= 326+2x < 480 94 <= 2x < 154 47 <= x < 77
*September 30, 2015*

**Calculus**

so, do you have a problem taking the partials and showing that they fit the equation?
*September 30, 2015*

**Maths**

1.76 + 760/6 t = 760/5 t t = 0.69 So, A overtakes B in .069 minutes. How many meters did A travel?
*September 30, 2015*

**math for managers**

costs are equal after x miles if 38000 + 0.24x = 35600 + 0.30x Now you need to know how many miles/year he drives.
*September 30, 2015*

**Math**

Actually, since they give you volumes, you have no idea how many grams are in solution! A 40% solution of NaCl would have a lot less mass of solute than a 40% solution of Fe2O3!
*September 30, 2015*

**math**

well, what's 10*10^5 ?
*September 30, 2015*

**Multivariable calculus**

dy/dx = (dy/dt)/(dx/dt) = (1+cost) / (e^t)(t+1) Kind of a cool curve, with a little scaling added: http://www.wolframalpha.com/input/?i=parametric+plot+x%3Dt%2F100+e^%28t%2F100%29%2C+y%3Dt%2F100%2Bsint
*September 30, 2015*

**Math**

clearly, p(success) = 801/1789 just express that as a decimal.
*September 30, 2015*

**math fractions**

4.25mi/0.875hr * 4.5hr = 21.86 mi or, using fractions (17/4 mi)/(7/8 hr) * (9/2 hr) = 17/4 * 8/7 * 9/2 = 153/7 = 21 6/7 mi
*September 30, 2015*

**math**

If she gets x right, then she gets 80-x wrong. That means we need 2x - 1/2 (80-x) >= 100 5/2 x - 40 >= 100 5/2 x >= 140 x >= 56
*September 30, 2015*

**Maths**

s(0) = 0 a little calculus (or inspection of the graph) will show that the runner changed direction at t=2.1 and t=7.4 s=10 when t≈10 http://www.wolframalpha.com/input/?i=plot+y%3D0.2t%28t+-+5.1%29%28t+-+9.1%29%2C+y%3D10
*September 30, 2015*

**pre algebra**

blue:red = (2/3):(3/4) = 2/3 * 4/3 = 8/9 after all, 2/3 = 8/12 and 3/4 = 9/12
*September 30, 2015*

**Go with Reiny**

Oops. I misread the problem.
*September 30, 2015*

**Norman**

If x is the smaller and y is the larger, y-x = 2 3x-y = 10 add them up and you get 2x = 12 x=6 so, y=8
*September 30, 2015*

**Math**

If x is the angle, 90-x is the complement. So, changing the words to math, you have x/2 = 25+(90-x)/3 Now just find x.
*September 30, 2015*

**math 5th**

15 = 3*5 so, what is 5*5? Or, if you must set up a proportion, 3/5 = 15/x 3x = 75 Now just find x.
*September 30, 2015*

**international school dammam**

using the quadratic formula, x = [7±√(49-20k)]/10 so, (7+√(49-20k))/10 * (7-√(49-20k))/10 = 1 49-(49-20k) = 100 20k = 100 k = 5
*September 30, 2015*

**algebra**

.80x = 80*1.30 x = 130
*September 30, 2015*

**Math?**

I'd go with 8.1 since the precision is apparently 0.1°C
*September 30, 2015*

**maths**

jeez. try using ^ for powers. (x^3-x^4+2x-1)-(x^4+x^3-2x^2+8) = x^3-x^4+2x-1-x^4-x^3+2x^2-9 = -2x^4 + 2x^2 + 2x - 9
*September 30, 2015*

**Math**

4000000/80000 = 400/8 = 50 You are correct. Either the answer key is wrong, or there's a typo in the problem.
*September 30, 2015*

**Math**

25ft * 8ft * 6ft = 1200 ft^3
*September 30, 2015*

**Geometry**

and you are correct. So, how do you know?
*September 30, 2015*

**Math**

These questions usually seem to use a time signature of 4/4. So, a quarter note is one beat.
*September 30, 2015*

**Music**

#1 2/4 + 1/4 = 3/4 #2 6/16 = 3/8
*September 30, 2015*

**Math**

that would naturally be -3*30
*September 30, 2015*

**futher mathematics**

x^2+y^2 = 6x x^2-6x + y^2 = 0 x^2-6x+9 + y^2 = 9 (x-3)^2 + y^2 = 3^2 x^2+y^2-6x+14y+49 = 0 x^2-6x + y^2+14y+49 = 0 x^2-6x+9 + y^2+14y+49 = 9 (x-3)^2 + (y+7)^2 = 3^2
*September 30, 2015*

**trig**

h/12 = tan 30° now just solve for h.
*September 30, 2015*

**math**

If any of us knew the formula, do you think we'd be spending our time here instead of spending our money in Hawaii?
*September 30, 2015*

**Integers and Algebraiac Expression**

words, words, words! If you want to write an essay, post a problem for the English tutors. This is math, so -12/3 * (-8+ (-4)^2 - 6) + 2 You will find this problem in the related questions below, in various states of accuracy. But continuing with the solution, we have -4 * (-8...
*September 30, 2015*

**college algebra**

since time = distance/speed, If she started out with speed x, then 242/x + 351/(x+10) = 12
*September 30, 2015*

**math**

Look up the conversion factor for feet-to-meters. Then multiply that by 19/3.
*September 30, 2015*

**Equation find x xo tricky**

or, (x^x)√x = x(√x^x) divide by x^x √x = x x=1
*September 30, 2015*

**Advanced function**

If x is the place to finish, and t is the time, t(x) = 125+5x for x=1,2,3 t(x) = 140+(168-140)/(10-3) x for x>3 = 140+4x
*September 30, 2015*

**math,(integral calculus)**

recall the power rule: ∫ x^n dx = 1/(n+1) x^(n+1) + C for derivatives, multiply by power and lower it for integrals, raise the power and divide by it.
*September 30, 2015*

**MATH**

Set up a common denominator: 20x Then add things up: 5x(x+2) + 4x(5x) + (2x+1) ----------------------- 20x Assuming I parsed your fractions correctly... As written, without parentheses, they add up to 81x/20 + 1/2
*September 30, 2015*

**MATH**

consider that x^2+4x+4 = (x+2)^2 so, the area is [(x+2)/4]^2
*September 30, 2015*

**MATH**

just multiply by 4 (a square has 4 sides!), and you get (h-2k)/4
*September 30, 2015*

**math**

well, 48/6 = 8, so ...
*September 30, 2015*

**Word problem maths**

If the oldest boy's age is x, then (14 3/12)*21 = (14 2/12)*20+x x = 15 11/12
*September 30, 2015*

**Word problem**

(7 35/60)*37*6 = 1683 hrs 30 min
*September 30, 2015*

**Mathematics**

Peter's share is 3/8 So, If the goods are worth x, we have x(3/8)(2/3) = 8000 Now just find x.
*September 30, 2015*

**Math**

No way. His average score for the first 4 games was 11 points. No way could he raise his average to 12 by just scoring another 11! You need to set it up like this: 14+9+10+11+x = 5*12
*September 30, 2015*

**math 5th**

what does it matter whether it was on a quiz? It's just a math problem. Is there something unsatisfactory with my response?
*September 30, 2015*

**math 5th**

multiply by 3/3 and you have 3/5 * 3/3 = 9/15
*September 30, 2015*

**Math**

since all the angles are equal 10*2 = 2x^2-8x
*September 30, 2015*

**Southridge**

since the differences are 3,5,7,9 and the 2nd differences are all 2, you expect a quadratic. A little thought shows that y = x^2+1
*September 29, 2015*

**Algebra II**

suppose I said x*20 = x*a would you not say a=20? Same here. Two powers of x are the same if the exponents are the same. Or, if you've ventured into logs, then you have 20 logx = a logx divide by logx and you have 20 = a This only fails if x=1, since then logx = 0, and you...
*September 29, 2015*

**math**

10 chairs per row: GCF(50,60)
*September 29, 2015*

**Math**

correct.
*September 29, 2015*

**Math**

the range is always (-∞,+∞) (if you allow both positive and negative roots of even powers) just look at the graphs.
*September 29, 2015*

**Algebra**

Oh, please! Surely you know that 1/4 = 2/8! If not, you have no business taking algebra.
*September 29, 2015*

**Algebra**

1/8 (3d-2) = 2/8 (d+5) 3d-2 = 2(d+5) can you take it from there?
*September 29, 2015*

**crump elm**

Explain? Heck, I can't even figure out the question. Have you ever heard of proofreading?
*September 29, 2015*

**Geometry**

well, if the small angle is 5x, then 5x+6x+7x = 180 Now just find x and figure the angles.
*September 29, 2015*

**MATHS**

If an empty crate weighs x, and a full crate contains y kg of fruit, then x + y/2 = 14 x + y/3 = 12 Now just find x.
*September 29, 2015*

**Simultaneous equation xo difficult**

I don't think you will find any solutions where all three are nonzero. So, play around with x+y = 2 x^2+y^2 = 3 x^3+y^3 = 5 Then you can use the fact that x^3+y^3 = (x+y)(x^2-xy+y^2) = 2(3-xy) = 5 You should get somewhere with that.
*September 29, 2015*

**vector**

just integrate each term, to get -cos(t) i + sin(t) j and evaluate at the limits.
*September 29, 2015*

**Sphere help**

Not sure what you're asking. If the volume is increased by x% (a factor of (1+x/100), it's because the diameter was increased by ∛(1+x/100) ≈ (1+x/300) or x/3 %
*September 29, 2015*

**7th grade math help**

19/20 = 95/100 = 0.95
*September 29, 2015*

**Math**

If there are x $2 bags, then the rest (5-x) are $5.50 bags. So, 2.00x + 5.50(5-x) = 17.00
*September 29, 2015*

**Algebra**

max height occurs when x = -b/2a Here, that means max height is where x = -(24/9) / (-8/9) = 3 so, find y(3)
*September 29, 2015*

**math**

really? Just remember that < means less than <= means less than or equal, or not more than, or at most > means greater than >= means greater than or equal, or not less than, or at least So, now you can easily see that #1: x >= 45 #4: 8-2 <= x <= 10-2 try ...
*September 29, 2015*

**Math (Help)!**

as usual, draw a diagram. The track consists of two parallel stretches (the length of the rectangle, x) and a complete circle (the two semi-circular ends, diameter y). 2x + πw = 200 Now, unless you can provide some more info, you can't determine x and y. The track ...
*September 29, 2015*

**Algebra**

second runner will lose.
*September 29, 2015*

**Calculus**

let u = x^2 du = 2x dx and your integrand becomes 1/2 sin(u) du for the 2nd one, use integration by parts u = x du = dx dv = sin x dx v = -cos x ∫u dv = uv - ∫v du ∫ x sinx dx = -x cos x + ∫cos x dx
*September 29, 2015*

**geometry**

use the distance formula to find the length of the diameter. Then, C = πd
*September 29, 2015*

**math**

a = .23 r = .01 S = .23/(1-.01) = .23/.99 = 23/99
*September 29, 2015*

**Math**

you know that log(u) has domain (0,∞) and range (-∞,+∞) So, log(x-3) has domain (x-3)>0 or x>3. That is (3,∞) range is still the same. Adding 1 to ∞ makes no difference.
*September 29, 2015*

**algebra**

If the speeds are x and y then x+y = 500.3 y = x+2.8 Now just substitute in for y, figure x, then get y.
*September 29, 2015*

**Math**

(y^4)(y^3) = y(4+3) = y^7 Powers are just shortcut for multiplication (y^4)(y^3) = (y*y*y*y)(y*y*y) = y*y*y*y*y*y*y = y^7
*September 29, 2015*

**Math**

let's see what they told you: r+b+a = 36 b-2 = 3(r-2) a+8 = 2(b+8) Now just solve for the ages.
*September 29, 2015*

**calc 2**

As you know, Newton's law says that your Temperature function is T(t) = 70 + 280e^-kt So, just solve for k in 70 + 280e^-20k = 210 then solve for t in using T(t) = 155.
*September 29, 2015*

**maths**

you can do it in base 10 because you know your multiplication table. To do it in base 12, you need to use a base-12 table. So, get out your pencil and paper and make one up. Or, if you have a unix system handy, run bc and use ibase=12 and obase=12. Then just enter your base-12...
*September 29, 2015*

**Math**

cis2x = (cis x)^2 cis3x = (cis x)^3 so, the quotient is 1/cis x
*September 29, 2015*

**Algebra**

2n + 3n-4
*September 29, 2015*

**algebra**

let u = x^(1/5) The equation then becomes u^2-8u+16 = 0 (u-4)^2 = 0 u = 4 so, x^(1/5) = 4 x = 4^5 = 1024
*September 29, 2015*

**Physics**

dat no de fomla R^2 = A^2 + B^2 Surely you could have looked that up in less time than posting here and waiting for a response...
*September 29, 2015*

**College Algebra**

-2^-3(xy^3)^-2 = -1/(8x^2y^6) x^-1y^-3 = 1/(xy^3) now divide (multiply by the reciprocal) and you have -1/(8x^2y^6) * xy^3 = -1/(xy^3) or, you can just do it like this -2^-3 (xy^3)^-2 (xy^3) = 1/8 (xy^3)^-1 = -1/(8xy^3)
*September 29, 2015*

**College algebra**

since you have no final numbers to work with, it means that your final formula will involve "h" standing for the height. See the problem solved at http://www.jiskha.com/display.cgi?id=1443498508 When you say you figured out the area, what did you do?
*September 29, 2015*

**College Algebra**

browsers override your text formatting. I think you meant 1/(4x-12) - 1/(2x-6) = 1/(x^2-3x) Factoring the denominators, you have 1/4(x-3) - 1/2(x-3) = 1/x(x-3) Clearly the LCD is 4x(x-3). So, using that LCD, you have in the top 1(x) - 1(2)(x) = 1(4) x-2x=4 x = -4 You can ...
*September 29, 2015*

**College Algebra**

You can always use wolframalpha.com to verify your work. For example, http://www.wolframalpha.com/input/?i=5x^2-10x%2B6%3D0 You got 10±√-2 That is clearly wrong. The formula states x = [-b±√(b^2-4ac)]/2a = [10±√(100-120)]/10 = (10±...
*September 29, 2015*

**College Algebra**

so, what don't you know abouth the formula? You have a = 5 b = -10 c = 6 Now just plug them into the formula.
*September 29, 2015*

**College algebra**

b = 2h-7 A = 1/2 bh = h(2h-7)/2
*September 28, 2015*

**ctu**

12474(1+r)^3 = 14001.00 r = 0.039 = 3.9%
*September 28, 2015*

**College Algebra**

If the smaller radius is r, then r+8 = 3r
*September 28, 2015*