Saturday

December 3, 2016
Total # Posts: 46,781

**Math**

Read what you posted. Fix it so it makes sense and try again.

*November 9, 2016*

**algebra**

(L-5) = 1/4 (K-5) L+K = 110 Now just solve. wait -- by 1/4 as young, do you mean 4 times as old? That could be a game changer...

*November 9, 2016*

**math**

as always, 2 times (length+width) = 24 ft + 84 in.

*November 9, 2016*

**math**

4/5 as much gas means 5/4 as much distance

*November 9, 2016*

**MATH**

well, twice the distance would be 2 inches, right? You have (375/200) times the distance, so ...

*November 9, 2016*

**math**

well, start with n Then n+12 then 2(n+12) then ... finally, solve the equation for n

*November 9, 2016*

**Pre Calc**

twice what amount? Read what you posted, and fix it so it makes sense.

*November 9, 2016*

**Maths**

(12000/400) * 9/4 minutes

*November 9, 2016*

**Maths**

5.14999999999999999999999999999994

*November 9, 2016*

**math**

342/14 round up if needed.

*November 8, 2016*

**Algebra 2**

well, did you graph the lines of the constraints, and shade the appropriate areas? This web site will solve the problem and even graph the solution if you want: http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html

*November 8, 2016*

**Math/algebra**

one expression is 10+5h

*November 8, 2016*

**Calculus**

You forgot the chain rule. F'(x) = ?(1+(x^2)^3)*(2x) - ?(1+x^3)*(1) F'(4) = ?(1+4096)(8)-?(1+64) visit this url and scroll down about halfway -- there is a good example with variable limits of integration. https://en.wikipedia.org/wiki/Leibniz_integral_rule

*November 8, 2016*

**math**

if the fractional part is less than 0.5, round down.

*November 8, 2016*

**Math**

2(2.5+2*.3 + 1.2+2*.3) = 9.8m or, the original perimeter plus two sides of each of the the four 30cm squares on the corners: 2(2.5+1.2) + 4(2*0.3) = 9.8

*November 8, 2016*

**math**

If the initial deposit was x, then compare the interest: .06(x+12000) = .05x + 1100 x = 38000

*November 8, 2016*

**math**

(3 3/4)(1 5/6) = 6 7/8

*November 8, 2016*

**Maths**

330m/s * 6s = 1980 m

*November 8, 2016*

**intermediate algebra**

since time = distance/speed, 24/s = 19/s + 1

*November 8, 2016*

**Maths**

total parts water: 2+3 total parts vinegar: 1+1 final ratio is 5:2

*November 8, 2016*

**Physics**

W = J/S = N-m/s So, in t seconds, 250*9.8*25/t = 4000

*November 8, 2016*

**Calculus AB - PS**

Rats. I made a typo near the top of #2. dy/dt = 1/(3?x^2) dx/dt (a) at x=8, 1 = 1/(3*4) dx/dt so, dx/dt = 12 at x=8, not 6. You will have to use that in the other parts. Also, in part (c) I made a typo. It should be sec^2? d?/dt = (-2/3)x^(-5/3) dx/dt, so d?/dt = -36/160

*November 8, 2016*

**Calculus AB**

(a) If the man is x feet from the light pole, and his shadow has length m, then using similar triangles. (x+m)/30 = m/6 In like wise, if the child's shadow has length c, then (x+10+c)/30 = c/3 So, we need to show that x+m > x+10+c when x=90 90+m=5m 90+10+c = 10c m=90/4...

*November 8, 2016*

**geometry**

Just like all the related questions below, The x,y distances from E to F are (10,-5) If G is 1/5 of the way from E to F, add 1/5 of the difference to E. G = (-4,9)+(2,-1) = (-2,8) If G is at the other end, subtract those values from F.

*November 8, 2016*

**Math**

(3.5)(2 2/5)(2.5-0.25) = 18.9 m^3 and it was probably concrete, not cement...

*November 8, 2016*

**math fraction**

It would look like a handful of candies, 1/3 of which were red. If there were n M&Ms, then n/3 would be red.

*November 8, 2016*

**Science**

If you've ever dropped sodium into water, you know that the reaction is violently exothermic.

*November 8, 2016*

**Maths**

f^2/g^2 = f^2 g^-2

*November 8, 2016*

**Math**

If the sum starts at the (k+1)st odd number, its sum is (k+288)^2 - k^2 = 576k + 82944 When k=432, the sum is 331,776 = 24^4 How you'd find that algebraically I have no clue.

*November 8, 2016*

**Math**

Since ??F = 8yk ? 0, F is not conservative.

*November 8, 2016*

**Math**

Did you not read what I wrote? g(0) is not defined, so f/g cannot be defined there. But x?0 is not one of the choices, so something is amiss.

*November 8, 2016*

**Math**

f/g = (|x|-1)/(1/x) = x(|x|-1) It would appear that the domain is all real x, but since g(0) is undefined, we have to exclude x=0. But x?0 is not one of the choices. Is there a typo somewhere? (f?g)(x) = f(g(x)) f(g) = (|g|-1) = (|1/x|-1) Again, x?0, so you are correct.

*November 8, 2016*

**Feelings**

about average

*November 8, 2016*

**Math**

You really need to start using parentheses online, to make things clear: 3/(x^2+x-2) - 1/(x^2-1) = 7/(2x^2+6x+4) Set everything over a common denominator of 2(x-1)(x+1)(x+2). Then, excluding the values of x = -2,-1,1 You just need to find 9-3x = 0

*November 8, 2016*

**maths**

(7/2)/(1/4) = 7/2 * 4 = 14 There are 7 half-liters. Each one contains 2 1/4-liters.

*November 8, 2016*

**Calculus**

Always be on the lookout for trick questions... Develop your inner laziness!

*November 8, 2016*

**Calculus**

Note that the series is collapsing. All the terms except the first and the last cancel out! (1/4 - 1/5) + (1/5 - 1/6) ... + (1/99 - 1/100) = 1/4 - 1/100

*November 8, 2016*

**algebra**

see related questions below. Add up your total so far. How many more to have 5*88 at the end?

*November 8, 2016*

**Math**

You are correct, but why list the values twice?

*November 8, 2016*

**Math**

Do you mean F(x,y) = e^(2x) + x^(2)yi + e^(2y) ? xy^2 j ? If so, then F•dr = (e^(2x) + x^2y) dx + (e^(2y) ? xy^2) dy That makes My = x^2 Nx = -y^2 ?F.dr = -??x^2+y^2 dy dx Using polar coordinates, that is just -??r^2 * r dr d? inside the circle: r = [0,2] ? = [0,2pi]

*November 8, 2016*

**Differential calculus**

Since the distance from the vertex to the directrix is 4, then the standard parabola x^2 = 4py has p=4. So, with the translation of the vertex to (3,-4), and the directrix above the vertex, the parabola opens downward, so the equation is (x-3)^2 = -16(y+4) confirmed at http://...

*November 8, 2016*

**Algebra**

well, x = 5y-19 use that in 7x-2y=32

*November 8, 2016*

**math**

2x^-5 = 2/x^5 2x^(-3/4) = 2/x^(3/4) a negative exponent just means shifting the value between numerator and denominator. Note that this also means that 2/x^(-2) = 2x^2 since that is 2 / (1/x^2) = 2 * x^2/1 = 2x^2

*November 8, 2016*

**Calculus**

Just substitute 6 for 1.8 in your time function. You will find that the shortest time is to boat all the way. A little analysis will show you that if the boat is faster than the running, the boat is the best way. If the ratio of the boat:run speed is k, then the distance ...

*November 8, 2016*

**science**

depends how far it slides. Just note the change in PE: mgh

*November 8, 2016*

**Math**

suppose that you allow 0/0 = x for some value x. Then, clearing fractions, 0 = 0*x But that is true for any value x. That is why 0/0 is not defined.

*November 8, 2016*

**Geometry**

Looks good.

*November 8, 2016*

**geometry**

see your other postings under different names.

*November 8, 2016*

**math geometry**

Mixing up problems, aren't you? Anyway, C's x-value is 3/7 of the way from 2 to 16. And try using the same name for all your postings.

*November 8, 2016*

**geometry**

X is 2/7 of the way from M to N. So, X's y-value will be 2/7 of the distance from 3 to 10. ...

*November 8, 2016*

**Math**

Note that the dog years grow by 4 for every increase of 1 human year. So, using the hint, so that at x=2, (x-2)=0, y = 4(x-2)+23

*November 8, 2016*

**Geometry (Please check my work)**

M->M', so the scale is 2/6, not 6/2

*November 8, 2016*

**Oral Literature = Oxymoron!**

!!

*November 8, 2016*

**Calculas-Differentiation**

I'll help you with the calculus: y'(x) = x-4 The rest is just Algebra I.

*November 8, 2016*

**math**

a+b+c

*November 8, 2016*

**math**

clearly its area is ?(x-1)^2 m^2

*November 8, 2016*

**Calculus**

If the cuts are length x, then the volume is v = (24-2x)(45-2x)(x) = 4x^3 - 138x^2 + 1080x dv/dx = 12x^2 - 276x + 1080 = 12(x^2-23x+90) = 12(x-18)(x-5) You can take it from there ...

*November 8, 2016*

**math**

how many in each pack

*November 8, 2016*

**Basic Calculus**

2(width+length)=240 width+length = 120 width = 120-length area = length*width = length*(120-length)

*November 8, 2016*

**dynmic**

a = s" = 4 F = ma

*November 8, 2016*

**algebra**

what? reposting after 11 minutes? What a waste of time for all.

*November 8, 2016*

**algebra**

you change the direction of the inequality when multiplying by negative values. This is just a shorthand way of moving terms from one side to the other: -2/5x - 9 < 9/10 -9 < 9/10 + 2/5x -9 - 9/10 < 2/5 x -9.9 < 2/5 x -9.9 * 5/2 < x -24.75 < x This is the ...

*November 8, 2016*

**math**

just use your formulas! ar^2 = (a + ar)/2 2r^2 = 1+r (2r+1)(r-1) = 0 Now you have r and a, and S = a/(1-r)

*November 8, 2016*

**time speed and distance**

A went 210 km in 3.5 hr (11:30) A stopped till 11:58 A then went on. So, A's position x in terms of time elapsed from 8:00 is x = 60t for 0 <= t <= 7/2 210 for 3.5 <= t <= 3 29/30 210+60(t-3 29/30) for t > 3 29/30 A reached Q at 11:58+0:55 = 12:53 B's ...

*November 7, 2016*

**calculus**

Did you draw the lines? You have a rectangle and a trapezoid. Surely you can handle that. Or, you can think of the figure as a small triangle and a large triangle.

*November 7, 2016*

**Calculus**

there are many Riemann Sum calculators online. google is your friend

*November 7, 2016*

**geometry**

You want E to be 3/4 of the way from C to D. So, for both x and y, you want to go 3/4 of the distance from C to D. The x-coordinates differ by 8 The y-coordinates differ by 4 So, you want to add (6,3) to C, making E=(1,2)+(6,3)=(7,5)

*November 7, 2016*

**Algrebra, Graphs, Math**

The equation represents a line. Two points determine a line. The easiest two points to find on the line are the axis intercepts. When x=0, y=3 When y=0, x=3 So, plot the points (0,3) and (3,0) and draw a line through them.

*November 7, 2016*

**precalc**

area of a sector is a = 1/2 r^2 ? so, the area is 1/2 ?(123/180) (24^2-3^2) = 608.6 in^2

*November 7, 2016*

**pre-calculus**

Po e^(20k) = 900 Po e^(30k) = 1600 e^(10k) = 16/9 k = 0.019 And you can take it from there, I assume.

*November 7, 2016*

**Math**

(1+r/100)^r = 1/9 no real solutions. Let's try simple interest: (r/100)*r = 1/9 r^2 = 100/9 r=10/3 = 3.33%

*November 7, 2016*

**math last question asap ples :P**

B: 5-12-13 is a right triangle since 5^2 + 12^2 = 13^2

*November 7, 2016*

**pre-calc.**

also, this is just the change of base formula, so ln(100)/ln(10) = log10100 = 2

*November 7, 2016*

**math**

41÷3 is a single value. Nothing can be "between" it Now, if you want two quotients with 41÷3 between them, then surely you can use 40÷3 and 42÷3 I think you need to review the problem and fix your posting.

*November 7, 2016*

**calculus**

Just use the power rule and the chain rule. y = u^n dy/dx = n u^(n-1) du/dx Now just plug in your u=2x+2 and crank it out. I might even go ahead and simplify it to y = 2^3 (x+1)^3 = 8(x+1)^3 Then du/dx = 1

*November 7, 2016*

**Math**

3 + 6*4 + 3 or 3 + 6*(4+3) the language is ambiguous

*November 7, 2016*

**Calculus**

Well, come on - is it Precal or calculus? Answer - It's Algebra 2. And stop reposting right away under a new topic, ok? What a waste of time. |a+bi| = ?(a^2+b^2)

*November 7, 2016*

**algebra 2**

That's "perform" I'll assume you know how to add and multiply polynomials for A-D. f(g) = 5g^3-2g = 5(3x^3)^3-2(3x^3) = 135x^9-6x^3 g(f) = 3f^3 = 3(5x^3-2x)^3 = 375x^9-450x^7+180x^5-24x^3

*November 7, 2016*

**geometry**

If the length is x, then 2*4*5 + 2*5x + 2*4x = 166 Now just solve for x

*November 7, 2016*

**Pre-Calculus**

Recall that |a+bi| = ?(a^2+b^2)

*November 7, 2016*

**Math 062**

The proportion is bogus x = 25*50 which is meaningless. You need either gal/gal = tanks/tanks 50/25 = x/1 x = # tanks needed or gal/tank = gal/tank 50/x = 25/1 x = # tanks needed

*November 7, 2016*

**maths help steve&reiny**

I guess the math gets a bit tricky, but just note that 97 = 81+16

*November 7, 2016*

**Vectors**

ships sail on headings, not bearings. A bearing is the direction of an object from your position. (It may also be your heading, if you are going directly there.) So, can you at least convert those times and speeds to distance vectors? Add them all up x-y wise and figure the ...

*November 7, 2016*

**calculus**

Ok, we've done a bunch of these for you. What ideas do you have? I'll get you started with f'(x) = -sin(x) cos(cos(x)) e^sin(cos(x)) The rest is just algebra and trig.

*November 7, 2016*

**pre algebra**

just shift the decimal point 5 places to the left.

*November 7, 2016*

**calculus**

the line has slope 2. So, a perpendicular to the line will have slope -1/2, which will be the slope of the radius. A line through (0,0) with slope -1/2 is y = -1/2 x. This line intersects the circle at (-2/?10 , 1/?10). Now just find the distance between that point and the ...

*November 7, 2016*

**calculus**

y = x^3+2x^2+bx y' = 3x^2+4x+b y'(1) = 3+4+b = 7+b y(1) = 1+2+b = 3+b So the line through (1,3+b) with slope 7+b is y-(3+b) = (7+b)(x-1) y = (7+b)x - 4 y=0 at x = 4/(7+b) So, under what condition will the tangent line(s) not intersect the x-axis? See an example for b...

*November 7, 2016*

**Calculas @Reiny**

Hey - everyone needs a hobby ...

*November 7, 2016*

**math**

Hmmm. Since there are 21 terms in the expansion, the 11th term is the middle one. Adjust the numbers accordingly.

*November 7, 2016*

**Pre-Algebra**

huh? Huh??? y = x/4 when x=40, y = 40/4 Stop guessing and start calculating...

*November 7, 2016*

**Pre-Algebra**

3 = 12/4 y=x/4, so ...

*November 7, 2016*

**Physics**

1% = 1/100 sheesh!

*November 7, 2016*

**Physics**

what, you've forgotten your algebra? Multiply by 100nto lear the fractions: R/n = nR/100 100R = n^2R 100 = n^2

*November 7, 2016*

**Physics**

If each resistor has value R, then R/n = nR/100 100 = n^2 n=10

*November 7, 2016*

**Calculas**

well, there is a horizontal asymptote at y = -3/4

*November 7, 2016*

**Calculus**

looks good. f(x) has a min when f' changes from - to + (f bottoms out and starts back up) That happens at x=2pi

*November 7, 2016*

**maths**

a group of 2 and a group of 3 takes 5 students. Clearly, 10 such pairs of groups can be formed.

*November 7, 2016*

**finance**

the net savings rate is 8% Now just plug that into your annuity formula with 35 years of deposits and 30 years of withdrawals. Of course, over 30 years, the 4% inflation will markedly reduce his buying power on a fixed income. A better model would provide for an increasing ...

*November 7, 2016*

**Calculas**

v = ?r^2h + 2/3 ?r^3 so, h = (v - 2/3 ?r^3)/?r^2 = v/(?r^2) - 2r/3 the surface area is a = ?r^2 + 2?rh + 2?r^2 = 3?r^2 + 2?r(v/(?r^2) - 2r/3) = 5?r^2/3 + 2v/r da/dt = 10?r/3 - 2v/r^2 = (10?r^3/3 - 2v)/r^2 da/dt=0 when 10?r^3/3 - 2v = 0 r^3 = 3v/(5?) and express h in terms of ...

*November 7, 2016*