Friday

November 27, 2015
Total # Posts: 35,808

**math**

GCF(18,20) = 2. So, at most 2 groups can be made.
*October 2, 2015*

**MATH**

so, what is the shortest side? Then find its midpoint. Just use the distance formula, and recall that the midpoint's coordinates are the average of the endpoints' coordinates.
*October 2, 2015*

**Business Math**

#1 (679.99-599.99)/679.99 = 0.1176 or about 12% #2 (15-12)/12 = 25% #3 extra revenue during that week was 15*599.99 - 12*679.99 = 839.97 So, ...
*October 2, 2015*

**physics**

well, in t seconds it falls 4.9t^2 meters. Looks like t≈1
*October 2, 2015*

**Calculus 1**

well, just do it normally: y' = 1/(9x^2+7y^2) * (18x+14yy') Now just factor out the y' stuff. Or, rewrite as e^y = 9x^2 + 7y^2 e^y y' = 18x + 14yy' y' = 18x/(e^y-14y) = 18x/(9x^2+7y^2-14y)
*October 2, 2015*

**Calculus 1**

y(x) = (9lnx)/x y'(x) = 9(1-lnx)/x^2 y'(1) = 9 y'(e) = 0 Now just use the point-slope form of the lines.
*October 2, 2015*

**Foley**

angle 1 + angle 2 = 90° But I'm sure Maddie caught that...
*October 2, 2015*

**Math**

well, they all add up to 360, so ...
*October 2, 2015*

**math**

you have it exactly backwards. To find out how many times 2 divides 10, you divide 10/2, not 2/10. So, 16.3/0.1 = 163
*October 2, 2015*

**physics**

E is in kg-m^2/s^2 p is in kg/m^3 A is in m^2 g is in m/s^2 So, we have kg-m^2/s^2 = kg^2/m^6 m^2/s^4 m^2 C kg-m^2/s^2 = kg^2/m^2-s^4 C C = (kg-m^2/s^2)(m^2-s^4/kg^2) = m^2-s^2/kg
*October 2, 2015*

**Maths**

(x-√2)(x+√2) = x^2-2 (2x^4+7x^3-19x^2-14x+30)/(x^2-2) = 2x^2+7x-15 Now you can factor that to find the other two roots
*October 2, 2015*

**Find x and y and also log**

2^x+y = 6 3^x-y = 4 6-2^x = 3^x-4 2^x+3^x = 10 A graphical solution is probably the best bet here. a^2+b^2=7ab a^2+2ab+b^2 = 9ab (a+b)^2 = 9ab 2log(a+b) = log 9ab log(a+b) = log(9ab)/2 = log√9ab = log√9 + log√ab = log3 + log(ab)/2 = log3 + (loga+logb)/2
*October 2, 2015*

**Math**

Does (0.025 + 1/2x) occur twice? It's hard to tell. If it does, and multiplies as written, then you just have 1.7 x 10^-3 = (0.0015 - x)^2 0.0015 - x = ±0.041 and that you can handle.
*October 2, 2015*

**Maths**

f(x) = x^2+8x-6 if the roots are 1/2 as much, then they are the roots of f(2x) = 4x^2+16x-6 I'll let you check with the quadratic formula.
*October 2, 2015*

**College Algebra**

clearly you are intended to use the Rational Zeroes Theorem, and start guessing. A little synthetic division reveals that there are no rational roots at all. So, the only possible roots will involve cube roots, and be very hard to find. I suggest graphing it and approximating ...
*October 2, 2015*

**Spanish**

Hi Sra! Could you please check my answers on these questions? 1) -Como quiera. Mientras Ud. ______ un sobre, yo limpiaré el compartimento. (MIRAR / BUSCAR) - Busque 2) Pero, por favor, antes de que Ud. se ________, (IR / VER) - Vayas 3) Cuando llegues (8) _____, ven (9...
*October 1, 2015*

**Math**

if it's air speed is 267 ft/s, then its vertical speed is 267 sin 16° = 73.595 ft/s So, to gain an altitude of 12500 ft takes 12500/73.595 = 169.848 seconds, or 2.83 minutes
*October 1, 2015*

**algebra**

the fraction left after d days is 0.5^(d/140) So, after 1 day, that is 0.99506 for a daily decay rate of 0.494% Now just plug in d=425
*October 1, 2015*

**Pre-calculus**

correct.
*October 1, 2015*

**Maths**

since it's a cubic, it's hard to do without calculus. The easiest way is to examine its graph. http://www.wolframalpha.com/input/?i=0.2t%28t-5.1%29%28t-9.1%29 Looks like t≈2.1 or 7.4
*October 1, 2015*

**Sequences and Series**

ahem. what is 25-3*8? minus, not plus.
*October 1, 2015*

**please help!!**

Assuming you meant f = (2x-6)/(x+1) using the quotient rule, f' = [(2)(x+1)-(2x-6)(1)]/(x+1)^2 so, at x=0, f' = (2+6)/2 = 4 Or, you can note that f = (2x-6)/(x+1) = 2 - 8/(x+1) so, f' = 8/(x+1)^2 f'(0) = 8/2 = 4
*October 1, 2015*

**math**

clearly it is 4160/x
*October 1, 2015*

**Math - eh?**

Try proofreading your posts.
*October 1, 2015*

**astronomy**

1 Watt = 1 J/s = 10^7 erg/s 1GW = 10^9 J/s the area of the sun is 4pi*(7*10^5 km)^2 = 6.2*10^12 km^2 So the solar output is 4*10^17 GW/6.2*10^12km^2 = 6.452*10^4 GW/km^2 So, now the question is: how much of that reaches the earth? I guess you need to use the inverse-square law...
*October 1, 2015*

**astronomy**

1/2 " = 2.424*10^-6 radians So, find r using s = rθ
*October 1, 2015*

**math?**

Not A: The contrapositive of X is if you don't raise your heart rate, you did not run for 10 min.
*October 1, 2015*

**AP Calculus**

if the rectangle is x wide by y high, then the diameter of the window is x. So x + 2y + π/2 x = 72 thus, y = [72-(1 + π/2)x]/2 The area is a = xy + π/8 x^2 = x[72-(1 + π/2)x]/2 + π/8 x^2 = 36x - (1+π/4)x^2 + π/8 x^2 = 36x - (1 + 3π/8)x^2...
*October 1, 2015*

**Help!! Geometric progression**

r=2, so you want a(2^(2n)-1) = 33a(2^n-1) n=5 ar * ar^3 = 2ar^4 a(r^4-1)/(r-1) = 80 a=2, r=3 GP: 2,6,18,54,162
*October 1, 2015*

**Math**

the same. You have just divided by m^4/m^4 = 1
*October 1, 2015*

**Physics**

clearly not, since you know that sound travels at roughly 373 m/s. Better double-check your math. Watch your units.
*October 1, 2015*

**functions**

no idea what differentiation of GIF means, but the derivative of a constant is zero (since constants do not change!). And, yes dx/dx = 1.
*October 1, 2015*

**Perumutation**

pick one of the antagonists. There are 8*7 ways to pick the two women next to her. There are 6! ways to arrange the other 6 women. So, 8*7*6! = 8! ways to seat the group.
*October 1, 2015*

**math**

at least means >= (not less) at most means <= (not more) #3: 8500 <= x <= 12000 #4 between usually includes the end points. So 6 <= x <= 8 #5: same idea #8: Using simple interest, 5000(1+10r) >= 1500 1+10r >= 1.30 10r >= 0.3 r >= 0.03 so, at least 3%
*October 1, 2015*

**algebra - eh?**

Fix the typo(s) You cannot add 100% antifreeze to 40% antifreeze and wind up with 25% antifreeze. Either you are adding water, or you have 10% antifreeze.
*October 1, 2015*

**Math**

well, which is greater -- 875 or 780?
*October 1, 2015*

**mass volume ratio**

so clearly each mole of Zn produces 1 mole of H2 6.5g = 0.1 mole Zn So, since 1 mole of H2 occupies 22.4L at STP, ...
*October 1, 2015*

**Math**

velocity v = ds/dt dx/dt = 2cos(t) dy/dt = -3sin(t) dz/dt = 1 acceleration a = dv/dt x" = -2sin(t) y" = -3cos(t) z" = 0 jerk j = da/dt x"' = -2cos(t) y"' = 3sin(t) z"' = 0
*October 1, 2015*

**pre-algebra**

cool. pretty small, eh?
*October 1, 2015*

**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*