Wednesday

February 22, 2017
Total # Posts: 48,712

**Pre-Calculus**

think about it. (x+y)^n has + signs for all the terms. (x-y)^n has minus signs for all the odd powers of n, since that is the same as (x + (-y))^n I'm sure you can provide your own examples. You might also try this web site: http://www.wolframalpha.com/input/?i=(x-y)%5E5 ...

*December 12, 2016*

**h.p.**

time to do some thinking, using what you already know. Your sum is ?k(k+1)(2k+1) = 2k^3 + 3k^2 + k = 2?k^3 + 3?k^2 + ?k These are just special sums whose formulas you already know.

*December 12, 2016*

**math**

what do you mean by "completes"? The sequence goes on forever, as indicated by the ellipsis. And, you don't provide any choices anyway...

*December 12, 2016*

**math**

y:g = 15:3 = 5:1 = 35:7

*December 12, 2016*

**h.p.**

Your sum is 1/2^2 (1/1.2 + 1/2.3 + 1/3.4 + ...) = 1/4 ? 1/(k(k+1)) Didn't we just do this?

*December 12, 2016*

**differentiation**

http://www.wolframalpha.com/input/?i=derivative+(x%5E3%2Byx%5E3)xy%3Dx%5E5-y%5E5

*December 12, 2016*

**differentiation**

(x^3+yx^3)xy=x^5-y^5 Hmmm. I'd pull out that x^3 first, giving (1+y)x^4y=x^5-y^5 (y')(x^4y)+(1+y)(4x^3y+x^4y') = 5x^4-5y^4y' Now expand some to get the y' terms: x^4yy' + (1+y)(4x^3y) + (1+y)(x^4y') = 5x^4-5y^4y' y'(x^4y + (1+y)x^4 + 5y^4...

*December 12, 2016*

**Geometry**

think of your standard 30-60-90 right triangle, and the ratios of its sides.

*December 12, 2016*

**h.p.**

what question? You have the sum correct.

*December 12, 2016*

**h.p.**

since 1+2+...+k = k(k+1)/2 Your sum is n ? 2/(k(k+1)) k=1 see what you can do with that. Note that 1/(k(k+1)) = 1/k - 1/k+1

*December 12, 2016*

**Pre-Calculus**

well, just look at the differences: 1st differences: -2 2 6 10 2nd differences: 4 4 4 Looks quadratic to me.

*December 12, 2016*

**precalculus**

well, you know that the parabola y^2 = 4px has vertex at (0,0) focus at x=p directrix at x = -p The vertex is halfway between the focus and the directrix, at (6,-2) So, shift it right 6, down 2. Then note that the distance from the focus to the directrix is 8-4=4=2p, and you ...

*December 12, 2016*

**precalculus**

nope. See your next post. Your parabola has focus (-5/2, -2) directrix x = 11/2

*December 12, 2016*

**math**

1 2/3 (4 5/6 + 7 8/9) = 21 11/54

*December 12, 2016*

**Calculus**

the radius r is given by r^2+h^2 = s^2 r^2+h^2 = 25 h = ?(25-r^2) v = ?/3 r^2 h = ?/3 r^2 ?(25-r^2) So, for maximum v, find r when dv/dr = 0

*December 12, 2016*

**Math**

no. The converse is unknown.

*December 12, 2016*

**Algebra**

rearrange the equations. You have x+7y=34 x+7y=32 Surely it is clear that there is no common solution.

*December 12, 2016*

**Pre-Calculus**

Just replace every k with k+1. No math involved.

*December 12, 2016*

**Calculus**

just because the graph is a horizontal line, it is not necessarily the line y = 0

*December 12, 2016*

**Math (please check my answer)**

wow. Your two answers are the givens. Way to go. vertical angles SAS

*December 12, 2016*

**precalculus**

actually, you are correct, since 5pi/3 is in QIV, so with r = -14, the point is in QII, with y positive.

*December 12, 2016*

**algebra**

diam=8, so r=4 area = 2?rh = 52 h = 52/(2?r) = 13/(2?) v = ?r^2 h = 16? * 13/(2?) = 104

*December 12, 2016*

**Physics**

This article should get you off the ground, as it were ... https://en.wikipedia.org/wiki/Trajectory

*December 12, 2016*

**math**

3+4+5 = 12 You want their sum to be 24, so double each value.

*December 12, 2016*

**HELP MATH**

14 4/10 - 10 5/10 = ?

*December 12, 2016*

**Pre-Calculus**

well, just add on a k+1 term. Looks like (A) to me

*December 11, 2016*

**math**

p = 3 s = 3(2 1/2) = 7 1/2 r = 3 - 3/4 = 2 1/4 t = (2 1/4)(1 1/3) = 3 now just add 'em up

*December 11, 2016*

**Algebra**

the new dimensions are 6w and 6h, so the area is 24 * 6^2

*December 11, 2016*

**calc**

lim (1 + 1/x)^x log lim = lim x log(1 + 1/x) = lim log(1 + 1/x) / (1/x) = lim (-1/(x^2+x)) / (-1/x^2) = lim x^2/(x^2+x) = 1 so, log lim = 1 lim = e^1 = e

*December 11, 2016*

**Algebra**

you are correct: 2(x+4)(x+3)= 3(x+2)(x-1) 2(x^2+7x+12) = 3(x^2+x-2) 2x^2+14x+24 = 3x^2+3x-6 x^2-11x-30 = 0 Now use the quadratic formula.

*December 11, 2016*

**Math! Help!**

the domain of all polynomials is (-?,?). Remember that.

*December 11, 2016*

**Math! Help!**

type in your polynomials here, and see the details. http://calc101.com/webMathematica/long-divide.jsp

*December 11, 2016*

**Algebra**

h(2h-3)/2 = 126 2h^2 - 3h - 252 = 0 you are correct

*December 11, 2016*

**precalculus**

nope. The standard form for a conic is r = ep/(1 ± e sin?) try again

*December 11, 2016*

**Algebra**

there is always a b. In this case, it is zero! 2x^2+16 = 0 2(x^2+8) = 0 2(x+?8 i)(x-?8 i) = 0 ...

*December 11, 2016*

**Algebra**

so, did you apply one of the methods? recall that (a+bi)(a-bi) = a^2+b^2

*December 11, 2016*

**Algebra**

complete the square quadratic formula

*December 11, 2016*

**English**

yes. watch the capitalization, though: I said, "Where do you live?"

*December 11, 2016*

**English**

1 and 2 are common, and equivalent. #3 means that it was necessary to stay -- not leave. #4 would get raised eyebrows and a "huh?"

*December 11, 2016*

**Geoemtry**

just subtract the picture area from the total, and that is the area of the frame: (x+2*2)(x+2*4)-x^2 = 65.25

*December 11, 2016*

**Geoemtry**

No idea. What is x supposed to represent?

*December 11, 2016*

**Algebra**

-12 >= x^2+8x x^2+8x+12 <= 0 (x+2)(x+6) <= 0 You know the roots are -2 and -6, and the parabola opens upward. So, y is negative between the roots: -6 <= x <= -2 Clearly Philip did not check his answer.

*December 11, 2016*

**Algebra 2**

m = ks^6 m/s^6 = k a constant If m is replaced with 15m, then you want a new s such that 15m/s^6 = m/2^6 s^6 = 15*2^6 s = 2*15^(1/6) = 3.14 mi/hr

*December 11, 2016*

**AP Calculus AB**

If x = side parallel to river y = other sides So, you want to maximize a = xy subject to 12x + 4*2y <= 3600 See what you can do with that.

*December 11, 2016*

**algebra 1**

Or, just note that a horizontal line is expressed by the equation y = k for some k. Since we have the point (-3,-7), the line is just y = -7

*December 11, 2016*

**algebra 1**

x = -5 is a vertical line. So, you want a horizontal line through (-3,-7) Now, what might that be?

*December 11, 2016*

**algebra**

you want 55x to be a perfect square 55 = 5*11 So, if x=55, 55x=55^2 = 3025 and the square root is 55 Any value of x that is 55 times a perfect square will also work.

*December 11, 2016*

**math check my answer please**

looks good to me.

*December 11, 2016*

**Algebra**

Nope. eq #2 is better to use to substitute. It says x = 6y+49 So, use that in eq #1, and you have 8(6y+49)-11y = 170 48y+392-11y = 170 37y = -222 y = -6 x = 6y+49 = -36+49 = 13 So, where did you go wrong? How did you make this step? -11y = 170-8x y = -15.45 + 72 what did you ...

*December 11, 2016*

**Math**

(a) No If it rains, I'll eat chicken. If it rains, I'll go outside. No way to conclude that eating chicken means going outside. (b) Come on. You know that the converse of p?q id q?p. So, ... (c) ~q ? ~r (d) Nope. I'm sure you can come up with an example. (Use what ...

*December 11, 2016*

**math**

the volume will be reduced by a factor of (1/3)(1/3)(1/3) = 1/27

*December 11, 2016*

**math**

LCM(12,18) = 36

*December 11, 2016*

**Math**

google can provide many discussions, all of which will be more complete than what we can provide here.

*December 11, 2016*

**Math**

(9/4)^2 * 48

*December 11, 2016*

**Calculus**

p = 2x+y a = 1/2 y ?(x^2 - (y/2)^2) = 1/2 (p-2x) ?(x^2 - ((p-2x)/2)^2) = 1/4 (p-2x)?(4px-p^2) da/dx = p(p-3x)/?(4px-p^2) da/dx=0 when p = 3x That is, when the triangle is equilateral. I expect you saw that coming, eh?

*December 11, 2016*

**Geoemtry**

if the two sides given are corresponding sides, then they have a common ratio: x/4 = 1/(2x+7) x(2x+7) = 4 2x^2+7x-4=0 (2x-1)(x+4) = 0 x = 1/2 so the triangles have sides of 4,8 and 1/2,1

*December 10, 2016*

**Algebra2**

right you are

*December 10, 2016*

**Algebra2**

Name the property of real numbers for -2(x+4)=-2x-8 associative property of multiplication communitive property of addition distributive property associate property of addition my answer is distributive property

*December 10, 2016*

**algebra word problem**

1100x + 1800y = 288 There is no unique solution. The rates can be anywhere from x=0 and y=16% to x=y=9.93%

*December 10, 2016*

**Algebra**

solve for t when h=0.

*December 10, 2016*

**Math (calculus) (mean values)**

I agree with the average rate of change. So, you want s'(c) = 1395/28 s'(t) = 1395/(t+2)^2 so, 1395/(c+2)^2 = 1395/28 (c+2)^2 = 28 c = ?28 - 2 ? 3.29 So, the desired month is later than 3, namely 4.

*December 10, 2016*

**Functions - math**

fg = (2x+3)(ax^2+b) = 6x^2-21 2ax^3+3ax^2+bx+3b = 6x^2-21 when x=q, we have 2aq^3+3aq^2+bq+3b=6q^2-21 2aq^3+(3a-6)q^2+bq+(3b-21) = 0 check out the solutions to that at this url. The only easy one is in fact when q = -3. http://www.wolframalpha.com/input/?i=2aq%5E3%2B(3a-6)q%...

*December 10, 2016*

**Science**

The axial tilt is what causes the seasons, but it does not change. The language of the question and the choices is poorly constructed.

*December 10, 2016*

**h.p.**

google is your friend. This should help. http://www.askiitians.com/forums/Algebra/22/42109/progressions.htm

*December 10, 2016*

**Algebra**

well, what is h when it hits the ground? ...

*December 10, 2016*

**Calculus**

when the water has depth y, the surface has with 4/3 y. That means the volume is v = y(4/3 y)/2 * 15 = 10y^2 dv/dt = 20y dy/dt Now just plug in your numbers to find dy/dt

*December 10, 2016*

**Algebra**

This is a trick question. |u| is always positive, so |1-4k| ? -11 for any value of k. Damon's solution is correct, but it should read k >= -2.5 OR k <= 3 So, any value of k will work.

*December 10, 2016*

**Math**

profit = revenue - cost revenue = price * demand P(x) = x(200-0.5x) - (100+5x+7x^2) = -7.5x^2 + 195x - 100 Now just find the vertex of that parabola.

*December 10, 2016*

**maths probability**

I hope he had fun.

*December 10, 2016*

**Math**

well, why do you not simply use the formula? i = P((1+r/n)^(nt)-1) and plug in your values?

*December 10, 2016*

**Math**

m/n= (m+b)/(n+b) m(n+b) = n(m+b) mn+mb = mn+nb b(m-n)=0 b=0 or m=n The question is poorly explained. It clearly said Does there exist a fraction(s) m/n... so offering a single example would indeed answer the question!

*December 10, 2016*

**Geometry**

15-9 < x < 15+9 so (C) is correct. If it were 24, then the triangle would collapse to just a line.

*December 10, 2016*

**Math**

4?/3 r^3 = 15000 r^3 = 45000/(4?) r = 10?(45/4?) or 5?(90/?)

*December 10, 2016*

**math**

area has the ratios squared, so 2^2:3^2 = 4:9

*December 10, 2016*

**Math.**

also 2:3

*December 10, 2016*

**math check my answer please**

Just as ?125 = 5?5, ?b^3 = b?b You went a bit astray, so we should have 3?(125a^1b^3) = 3*5b?(5ab) = 15b?(5ab) The 3 does not distribute across products. The distributive property only applies to addition, as in 3(?a + ?b) = 3?a + 3?b

*December 9, 2016*

**soil mechanic**

um ?

*December 9, 2016*

**math help**

?(48ab^2) = ?48 * ?a * ?b^2 = ?16 * ?3 * ?a * b = 4b?(3a)

*December 9, 2016*

**Math**

sorry. You have the equation. Plug in the given x or y value and solve for e or f. You gotta do something here, dontcha? Stop looking for freebies...

*December 9, 2016*

**Math**

Assume a straight line. As x increases by 2 (5-7) y increases by 6 (13-19). So try y = 3x But, 13 - 3*5-2. So, try y = 3x-2 it works for all the known pairs. So, fill in e and f.

*December 9, 2016*

**Math**

correct.

*December 9, 2016*

**Math**

Nope. The slopes are 1 and -1, so their product is -1. That means they are perpendicular.

*December 9, 2016*

**geometry**

google is your friend. Try this: https://www.algebra.com/algebra/homework/word/geometry/Angle-bisectors-in-an-isosceles-triangle.lesson

*December 9, 2016*

**Geometry**

ABE+ABC = 180, so ABC = 180-ABE ABC = (180-y)/2 so, 180-(3x+20) = (180-y)/2 160-3x = 90 - y/2 70-3x = -y/2 y = 6x-140

*December 9, 2016*

**math**

no, m+5m = 6m cm area is m*5m = 5m^2 cm^2

*December 9, 2016*

**math**

I don't know what you mean by "solve" it. It's just an expression. No equation. (0.08b^{4m+8})/(18b^{m?2}) = .08/18 b^(4m+8-(m-2)) = 1/225 b^(3m+10) 1/(1/5) m^(4-n) * 1/2 m^(n-6) = 5/(2m^2)

*December 9, 2016*

**Calculus**

and ... ?

*December 9, 2016*

**Algebra**

Draw the line. It lies in QII, QI, QIV

*December 9, 2016*

**precalculus**

divide by -2 ant it changes to r = -2/(1+3sin?) now what do you think?

*December 9, 2016*

**precalculus**

since tan?/sec? = sin?, can you handle r sin? = 2 ??

*December 9, 2016*

**Algebra 1**

yep.

*December 9, 2016*

**precalculus**

the standard equation is r = ep/(1 - e sin?) so, if you divide top and bottom by -2 you get r = -2/(1+3sin?)

*December 9, 2016*

**precalculus**

tan?/sec? = sin? so, can you convert r sin? = 2 ??

*December 9, 2016*

**math**

if the cuboid has sides x,y,z, then the main diagonal d has length d^2 = x^2+y^2+z^2

*December 9, 2016*

**math**

That is really a=p(1+r/n)^(nt) Assuming you mean compounded quarterly, just plug in your numbers, with r=0.043 n=4 t=6

*December 9, 2016*

**Math**

f+t = 26 5f+10t = 210

*December 9, 2016*

**Algebra**

well, that would be 2/9 * 2493, right?

*December 9, 2016*

**Quadratic Relations, Algebra, Math**

solve for h = 0.5 -4.9t^2+14t+2.5 = 0.5 now just use the quadratic formula.

*December 8, 2016*

**math**

Cause the exponent is positive you move the decimal point 3 places to the right so that would = 1900

*December 8, 2016*

**Algebra**

12.50-8.75=3.75 You have $3.75 left for toppings $1.25*3=3.75 You can have 3 toppings

*December 8, 2016*