Monday

December 22, 2014

December 22, 2014

Total # Posts: 27,667

**science**

the same
*November 13, 2014*

**Math *checking answers*?**

Nope - my bad. B,C,D are all the same You want 9.5/3 = x/7 but B,C,D are all 9.5/3 = 7/x
*November 13, 2014*

**Math *checking answers*?**

I like C for #2. It's the same as 9.5/3 = x/7
*November 13, 2014*

**calc**

I think you want g(x) = 3x√(x+5) on [-5,0] g(-5) = 0 g(0) = 0 So, we want c somewhere in (-5,0) such that f'(c) = 0 f'(x) = 3(3x+10) / 2√(x+5) f' = 0 when 3x+10 = 0 So, c = -10/3 which is in the domain.
*November 13, 2014*

**calc**

In that case, g(0) = 0 g(5) = 15√10 Again Rolle's Theorem does not apply. Try again.
*November 13, 2014*

**calc - eh?**

g(0) is not defined, since sqrt(-5) is not real. So, g(x) does not satisfy the condition that g(0) = 0 You want to reconsider any part of the question?
*November 13, 2014*

**MATH HELP PLEASE**

(13/4)(2x + 3/4) (13/4)(2x) + 13/4 * 3/4 (13/2)x + 39/16
*November 13, 2014*

**Math: Chi Squared**

Boy, you don't give much context, do you?
*November 13, 2014*

**Intermediate Algebra**

clearly the domain is not (-oo,100) negative percent makes no sense. I'd say the domain is [0,100) C(X) -> oo as x->100, meaning that the harder you try to squeeze out that last bit of pollution, the morse it costs. So, just evaluate C(90). Then double that, since we...
*November 13, 2014*

**Algebra**

-3x^5 + 24x^2 factor out -3x^2 and you have (-3x^2)(x^3) + (-3x^2)(-8) -3x^2 (x^3-8) Now recall the factorization of the difference of two cubes, and you have -3x^2(x-2)(x^2+2x+4)
*November 13, 2014*

**Science**

F = ma so, a = F/m the x-component is F cos60° and sine for y
*November 13, 2014*

**Molecular Calculations**

convert g of Sn to moles. You will need that many moles of O2. Then find the mass for that many moles of O2.
*November 13, 2014*

**Algebra 2**

7x^2 = 21x 7x^2-21x = 0 7x(x-3) = 0 This is why we always set stuff to zero. If the product of factors is zero, one of the factors must be zero. So, we have 7=0: never x=0: x=0 x-3 = 0: x=3 Those are the solutions: x = 0 or 3
*November 13, 2014*

**math**

0.8 = 8/9 So, you have 10.1 + 8/90 = 101/10 + 8/90 = 917/90
*November 13, 2014*

**Calculus**

yes
*November 12, 2014*

**math**

at any depth y, the radius of the surface of the water is y/2. So, v = pi/3 (y/2)^2 y = pi/12 y^3 dv/dt = pi/4 y^2 dy/dt Now plug in your numbers.
*November 12, 2014*

**Calculus - PLEASE HELP!!**

Looks good to me
*November 12, 2014*

**math**

(6.0-0.3)/4
*November 12, 2014*

**Inverses of functions**

f^-1(a-1) = -3 a-1 = f(-3) a-1 = 2 a = 3 Not sure just what you're asking
*November 12, 2014*

**math**

b/g = 8/5 b = g+135 now just solve for g
*November 12, 2014*

**Pre-Calculus**

Look what happens when x gets huge. The equation is basically 5y^2 = 20x^2 y^2 = 4x^2 so the slopes are 2 and -2
*November 12, 2014*

**Math**

x-25.6 = 84.3
*November 12, 2014*

**Math**

m-4=11 m+u=53 now just find u
*November 12, 2014*

**Math**

(100-50)/(3-1.5)
*November 12, 2014*

**Science**

you are correct
*November 12, 2014*

**math**

s=m m = 4(s-18) Each had 24
*November 12, 2014*

**Pre-Calc/Trig**

range is all positive >2, as well as all negative On the interval (-1,1) the numerator is positive and the denominator is negative.
*November 12, 2014*

**Math HELP!**

x-10 = 47 x-25.6 = 84.3
*November 12, 2014*

**Algebra HELP!**

If the population is P, then 14/50 * P = 30
*November 12, 2014*

**Math - eh?**

eh? try that in English
*November 12, 2014*

**Arithmetic Progression**

a + a+d = 4 a+9d = 19 a=1 d=2 So, now add T5 and T6
*November 12, 2014*

**Algebra**

the two roots have product c and sum 7 Since the coefficient of x is 1, all the rational roots are integers. (x-1)(x-6) = x^2-7x+6 (x-2)(x-5) = x^2-7x+10 ... I think you can see that there are only a few values for c.
*November 12, 2014*

**Calculus**

∫v(v^3+5)^2 dv = ∫v(v^6 + 10v^3 + 25) dv = ∫v^7 + 10v^4 + 25v Now just integrate each term.
*November 12, 2014*

**caculus**

f"(x) = -4sin(2x) f'(x) = 2cos(2x) + c1 f(x) = sin(2x) + c1*x + c2 Now plug in the initial conditions to find c1 and c2
*November 12, 2014*

**calculus**

a(t) = 36t+10 v(t) = 18t^2+10t+c v(0)=9, so c=9 and v(t) = 18t^2+10t+9 s(t) = 6t^3+5t^2+9t+c s(0) = 16, so c=16 and s(t) = 6t^3+5t^2+9t+16 So, find s(11)
*November 12, 2014*

**Calculus**

Try this site: http://mathworld.wolfram.com/RiemannSum.html
*November 12, 2014*

**alg 2**

think back to algebra I. The QF is x = [-b +/- sqrt(b^2-4a)]/2a So, just plug in your number. The first is x = [-4 +/- sqrt(16-4(1)(-2)]/2 = [-4 +/- sqrt(16+8)]/2 = -4 +/- sqrt(24)]/2 = -2 +/- sqrt(6) Do the same with the others. First step is to get everything on the left ...
*November 12, 2014*

**Algebra 2 HELP plz**

t=2 is the correct time. So, plug in t=2 for your formula for h to get the max height. to see when it hits the ground, just set h=0: -16t^2+64t+80 = 0 -16(t+1)(t-5) = 0 so, h=0 at t=5
*November 12, 2014*

**Pre-Calc/Trig...**

2(x+5)/(x-3)
*November 12, 2014*

**College Algebra**

This is just a parabola, with its vertex at h = -b/2a, or in this case h = 3.817/0.14
*November 12, 2014*

**Math**

w(3w-5) = 12 ...
*November 12, 2014*

**College Algebra**

y = a(x+2)(x-8) The vertex is midway between the roots, at x=3, so y(3) = 5 a(5)(-5) = 5 a = -1/5 y = -1/5 (x+2)(x-8) See http://www.wolframalpha.com/input/?i=-1%2F5+%28x%2B2%29%28x-8%29
*November 12, 2014*

**College Algebra**

usually college algebra students haven't learned about derivatives. However, s(t) is just a parabola, with its vertex at t = 112/32 so, plug that into s(t) to find the max height Note that you got your derivative wrong, anyway.
*November 12, 2014*

**algebra**

if x at 2%, then the rest (10000-x) at 5%. So, 10000-x = 3x so solve for x, and the interest earned is .02x + .10(3x) = ?
*November 12, 2014*

**algebra**

y = ab^x a*b^2 = 3 a*b^9 = 33 a = 3/b^2, so a*b^9 = 3/b^2 * b^9 = 3b^7 = 33 b = 11^(1/7) a = 3/11^(2/7) y = 3/11^(2/7) * 11^(x/7) = 3*11^((x-2)/7) y(15) = 3*11^(13/7) = k
*November 12, 2014*

**math olympiad**

there are many such rectangles. 1 x √88 2 x √85 ... √44 x √45
*November 12, 2014*

**intermediate algebra**

the line through (2,3) and (2,0) is x = 2 That is a vertical line. So, the perpendicular line through (2,3) is y = 3
*November 12, 2014*

**Maths**

h/10 = 1.8/1.2
*November 12, 2014*

**St Ans School**

75-x = x-45 ...
*November 12, 2014*

**Math**

How about writing that as 3x - 8y - 4 = 0
*November 12, 2014*

**Math Help**

ln√x-8=5 ln√x=13 √x = e^13 x = e^26 log2x+log2(x+2)=log2(x+6) log2(x(x+2)) = log2(x+6) x(x+2) = x+6 x^2+2x = x+6 x^2+x-6 = 0 (x-2)(x+3) = 0 x = 2 or -3 But, log2(x) is not defined for x <= 0, so x=2 is the only solution check: log2(2)+log2(2+2) = log2(2+6...
*November 12, 2014*

**Math**

if course not "all reals" plug in just some value and see whether the equation balances. In particular, try x=0: log(4) =?= log(2) I don't think so. What you need to realize is that if 2^x = 2^y or log2(x) = log2(y) or 2x = 2y or 2+x = 2+y or in general, for any ...
*November 12, 2014*

**Maths**

1.3/1.8 = h/(7+1.8)
*November 12, 2014*

**Math**

you want e^.12x = 3
*November 12, 2014*

**maths**

a:b = 3:5 = 12:20 b:c = 4:7 = 20:35 a:b:c = 12:20:35
*November 12, 2014*

**math algebra**

Hard to tell, but it appears that you have (x-3)/4 - (y-2)/5 = -1/4 (4-x)/3 + (3-y)/2 = -13/20 which is the same as 5x - 4y = 2 20x + 30y = 209 20x-16y = 8 20x+30y = 209 46y = 201 so, x = 448/115 y = 201/46 Hmmm. Maybe you had x - 3/4 - y - 2/5 = -1/4 4 - x/3 + 3 - y/2 = -13/...
*November 12, 2014*

**Pre-Calculus**

recall that cos 2x = cos^2 x - sin^2 x
*November 12, 2014*

**Pre-Calculus**

7/12 = 1/3 + 1/4 now review your addition formula for tan(x+y)
*November 12, 2014*

**Pre-Calculus**

recall that cos(x-y) = cosxcosy+sinxsiny hence the name cosine -- sine of complementary angle
*November 12, 2014*

**maths**

we need (1+x)(0.9) = 1.08 x = 0.20 = 20% check: on $1.00 cost, mark up to $1.20 discount = $0.12, so the final price is $1.08, or 8% profit
*November 12, 2014*

**Pre-Calculus**

cos(cos^2+sin^2) don't forget your Algebra I now that you're taking trig!
*November 12, 2014*

**Math**

surely the explanation in your text will be more thorough than any offered here. Also, google is your friend...
*November 12, 2014*

**Geometry**

s = rθ, so θ = s/r
*November 11, 2014*

**math**

12 and 15
*November 11, 2014*

**math**

yes, you did
*November 11, 2014*

**Calculus**

just use the power rule: d/dx(x^n) = n x^(n-1) so, f'(x) = 3x^2 + 5/x^2
*November 11, 2014*

**Geometry**

No, it's November 11. I think you need to provide a little more context. p -> q where p=It's snowing today and q=It is December
*November 11, 2014*

**math**

Assuming that's $2.90 each, then 2*2.9 = 5.80 So, now, which has cost more for two packs of batteries?
*November 11, 2014*

**calculus related rates**

PV = k V dP/dt + P dV/dt = 0 dP/dt = -(P/V) dV/dt Now just plug in your numbers. By the way, this is true only if the temperature remains constant. More generally, PV = kT
*November 11, 2014*

**calculus inverted cone**

when the contents have depth y, the radius of the surface of the liquid is y/2 So, v = pi/3 r^2 y = pi/3 (y/2)^2 y = pi/12 y^3 dv/dt = pi/4 r^2 dy/dt Now just plug in your numbers.
*November 11, 2014*

**Math**

e+s = 80 e-17 = 2(2/3 s) Now just solve for e and s, and then get e-s.
*November 11, 2014*

**Math**

looks ok. But that depends on what x represents...
*November 11, 2014*

**Math**

9^2+35
*November 11, 2014*

**Math**

5 * 50/(5+8+7) = 12.5 m
*November 11, 2014*

**College Algebra**

there are lots of good graphing sites. Try here: http://www.wolframalpha.com/input/?i=plot+y%3D1%2F2x-3 The two equations describe the same line.
*November 11, 2014*

**Advanced Algebra**

3x=4(4-2x)=11 I suspect a typo
*November 11, 2014*

**Pre-Calc/Trig**

extrema where 12x^2 - 24x = 0 12x(x-2) = 0 Now apply the 2nd derivative test, and what you know about the general shape of cubics.
*November 11, 2014*

**math**

I suspect that V = XYZ So, just multiply the three values
*November 11, 2014*

**Calculus**

Go to http://www.wolframalpha.com/input/?i=8ln%28sec%28x%29%29+ and scroll down a bit.
*November 11, 2014*

**Derivatives**

Hmmm. You have y = uv, so y' = u'v+uv' = 3x^2(5x-1)^4 + x^3 * 4(5x-1)^3(5) = x^2(5x-1)^3 (3(5x-1) + 20x) = x^2(35x-3)(5x-1)^3
*November 11, 2014*

**Geometry**

if the circle has diameter d, then the square has sides equal to the diameter. area = d^2
*November 11, 2014*

**Pre-Calc/Trig**

x^5 is positive for x>0 and negative for x<0. So, the graph curves down on the left, and up on the right. All you really need to look at is the highest power of x, which dominates everything for large values of x.
*November 11, 2014*

**math - oops**

Oops. That is Nx - My I'll let you make the change and redo the arithmetic.
*November 11, 2014*

**math**

Green's Theorem says that ∮CMdx+Ndy = ∫∫RMx+Ny dx dy Nx = 8xy My = 2xy So, we end up with ∫[0,2]∫[x,2x] 10xy dy dx = ∫[0,2] 5xy^2 [x,2x] dx = ∫[0,2] 5x(4x^2-x^2) dx = ∫[0,2] 15x^3 dx = 5x^4 [0,2] = 80
*November 11, 2014*

**algebra 2**

Just as with normal fractions, you need to find a common denominator. For example, with 2/3 + 3/5, the commond denominator is (3)(5) Here, you will have a common denominator of (x+y)(x-y) So, you will wind up with (x-y)(x-y)/(x+y)(x-y) + (x+y)(x+y)/(x-y)(x+y) = [(x-y)^2 + (x+y...
*November 11, 2014*

**math**

telepathy
*November 11, 2014*

**Algebra please help answer ASAP**

(A) 5km/.5hr = 10.0 km/hr (B) 20km/.8hr = 25.0 km/hr (C) 10.0+25.0 = 35.0 km
*November 11, 2014*

**Algebra please help answer thx**

1/4 of the guitarists play jazz, so 3/4 play classical. So, 3/4 * 5/8 * 64 = 30
*November 11, 2014*

**math**

you are correct, because 6 and23 have no common factors
*November 11, 2014*

**math**

every 12 minutes both change at the same time.
*November 11, 2014*

**Math**

every 35 days the schedules coincide
*November 11, 2014*

**Precalc/Trig**

The first 4 are all ok cot is negative in QII and QIV, and you are right about π±θ. But, that θ is the reference angle, which is always in QI. θ = arccot(5), not -5.
*November 11, 2014*

**Math**

(-x+4)log11 = (3x-2)log5 -log11 x + 4log11 = 3log5 x - 2log5 -(log11+3log5)x = -(2log5 + 4log11) x = (2log5+4log11)/(log11+3log5) and, of course, you could go on and say x = log(5^2*11^4)/log(11*5^3) = log366025/log1375 or even log1375366025
*November 11, 2014*

**Grammar**

more in keeping with the original might be: The medication had a noticeable positive effect on the patient.
*November 11, 2014*

**physics**

Snell's Law says that sinθ/sin30° = 1/1.33
*November 11, 2014*

**math**

3 whites out of 10 total balls makes P(white) = 3/10
*November 10, 2014*

**Calculus**

Not sure why there are two = signs. Also, Phi is usually an angle, unless it is the golden ratio. I've never seen either one raised to such a power. Where did you get the "equation"?
*November 10, 2014*

**algebra**

both domain and range are (-∞,+∞) the domain for all polynomials is the same.
*November 10, 2014*

**Calculus**

so, why toss in the product rule as well? :-)
*November 10, 2014*

**calc/trig**

to find θ, note that tanθ = 84/130
*November 10, 2014*

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