Tuesday

January 27, 2015

January 27, 2015

Total # Posts: 28,400

**Math**

It appears that the chopped piece fell 4 feet. So, the tree was 4+7=11 feet tall.
*January 24, 2015*

**physics**

the height of the falling stone is 6.82-8.8t-4.9t^2 the height of the stone thrown upward is 8.8t - 4.9t^2 So, when do they meet? At t=0.3875 Now plug that into either function to get the height at that time. http://www.wolframalpha.com/input/?i=solve+6.82-8.8t-4.9t^2++%3D++8....
*January 24, 2015*

**physical**

√((300+400/√2)^2+(400/√2)^2)
*January 24, 2015*

**maths**

34.67*10^-6 pN/m^2 * 1.0197*10^17 lb/pN * 2.59*10^6m^2/mi^2 = 9.16*10^18 lb/mi^2
*January 24, 2015*

**Set Question 1**

Since A∩(BC) = A∩B ∪ A∩C, your first step is (X ∪ Y ∪ Z)∩X ∪ (X ∪ Y ∪ Z)∩(Y∩Z) and now break down each of those similarly. Just review your basic set properties. Recall that X∪X = X∩X = X
*January 24, 2015*

**Trignometery**

As usual, draw a diagram. If we label Kappy=K Blue UFO=B Red UFO=R KR = 42 tan64° + 42 tan 12° UV = 42(sec 12°)
*January 24, 2015*

**Algebra**

39,916,799 http://www.wolframalpha.com/input/?i=sum+n*n!+for+n%3D1+to+10
*January 24, 2015*

**Geometry**

the tangent at P has slope x/(2a) So, the normal line is y-ap^2 = p/(2a) (x-2ap) y = p/(2a)(x-2ap)+ap^2 So, where does that line intersect y = x^2/(4a) ? p/(2a)(x-2ap)+ap^2 = x^2/4a (1/4a)x^2 - p/(2a)x + p^2(1-a) = 0 Now just solve that for x and figure y. One solution better ...
*January 24, 2015*

**math**

no idea. where did you leave off? Just start with 8 and keep adding 3
*January 24, 2015*

**Math**

1A reflection in the x-axis changes the sign of y. parent: x^3 flip over x: -x^3 raise 2: -x^3+2 2C y becomes taller, which has the equivalent effect of making the graph look narrower. parent: x^2 shift right (x-2)^2 flip over x: -(x-2)^2 stretch up (make narrower): 3(x-2)^2 ...
*January 24, 2015*

**math**

If the rectangle's dimensions are x and y, and the square is side s, then 2x+2y = 4s 2(x+y) = 96 x = s-4 2(x+y) = 2x+2y = 4s = 96 so, s = 24 x = s-4 = 20, so y = 28 2xy = 2*20*28 = 1120
*January 24, 2015*

**math**

If the cardboard has side x, the volume is (x-8)^2*4 = 324 Now it is clear what x is.
*January 24, 2015*

**algebra**

(x - 1/5)^2
*January 23, 2015*

**Maths**

a = 4 d = 11 n = (368-4)/7 + 1 = 53 S53 = 53/2 (4+368) = ?
*January 23, 2015*

**algebra**

Using feet for all measurements, we have 18 * 3/4 * length = 4*27*4 length = 32 ft
*January 23, 2015*

**algebra**

2.50(5/4) + 5.50(3/4) = x(5/4 + 3/4) x = $3.625
*January 23, 2015*

**applied math**

width is 10*12 = 120 inches So, it takes 120/4 widths Since the wall is an exact number of widths, we just need to figure the length to find the rolls. 10*12*4 = 480 in long so, we need 480/(20*12) = 2 rolls Makes sense, since each roll does 2 strips, and we need 4 strips.
*January 23, 2015*

**algebra**

I get 0.808
*January 23, 2015*

**Math**

P = (8,-3) The slope of PQ is ∆y/∆x = (3/(7-x)-(-3))/(x-8) = (3+3(7-x))/((7-x)(x-8)) = (24-3x)/((7-x)(x-8)) You have provided no data about Q or the desired slope, but just plug in the numbers you have.
*January 23, 2015*

**math**

using the two-point form of a line, you have (p-59) = (42-59)/(50-32) * (q-32) Now just rearrange that into p = 1/18 (1606-17q)
*January 23, 2015*

**Algebra 1**

You know two things: g+s = 425 g = s+25
*January 23, 2015*

**college algebra**

just solve for t in 16t^2 = 128
*January 23, 2015*

**Math**

you have a right triangle with legs 4 and 6. The hypotenuse is thus 2√13. I don't see any good choices.
*January 23, 2015*

**math**

you have the line intersecting when kx^2-5x+2 = -3x+4 kx^2-2x-2 = 0 Now recall the discriminant, d=b^2-4ac If d>0 there are two roots If d=0, there is one root If d<0 there are no real roots. The discriminant of your equation is 4+8k I expect you can determine when that ...
*January 23, 2015*

**Math**

if it takes t seconds to flip it once, then the actual flipping will take 10,000*t or 100,000*t seconds. There are 86,400 seconds in a day, if that helps.
*January 23, 2015*

**math**

a = 12 d = -6 T30 = a+29d so, . . .
*January 23, 2015*

**math**

I love it when you guys as us to show our work. Ever think of showing some of yours? y' = 6x+4 The line given has slope -2. So, when do we have 6x+4 = -2? x = -1 y(-1) = -2, so we want the point (1,-2) to be on the line. That means -2 = -2(-1)+b b = -4 See the graphs at ...
*January 23, 2015*

**College Algebra**

6400(1+.005/12)^(12*7) = $6627.92
*January 23, 2015*

**Math**

I'll do one, and you follow the steps for the other. 2cosx + √2 = 0 cosx = -√2/2 = -1/√2 x = π/4 on the unit circle, x = cosθ and y = sinθ, so the location is (-1/√2,1/√2) or (-1/√2,-1/√2) (QII or QIII) as usual, ...
*January 23, 2015*

**integrated physics and chemistry**

(12-20 m/s)/(32s) = -8/32 = -0.25 m/s^2 However, as the car was going north and slowed down, its acceleration was in the south direction.
*January 23, 2015*

**maths**

s = rθ you have r and θ, so plug them in (θ in radians). That will give you the actual arc length traveled. If you want the horizontal distance, assuming symmetry, then you will need x/2 = r sin(θ/2)
*January 23, 2015*

**math**

just equate the two: 2x^2-2x-3 = -x^2-2x-3 2x^2 = -x^2 x = 0 so, y = -3
*January 23, 2015*

**math**

clearly it is a geometric series, with a = 2 r = 3/7 So, use your summation formula for GP's: Sn = a(1-r^n)/(1-r) and plug in a and r.
*January 23, 2015*

**Maths - eh?**

No idea what xsq is. x^2? And what is the triple "xsq, ysq, z,sq" supposed to mean? I'll use © for the operator. You say (x,y,z)© = xsq, ysq, z,sq I have no idea what that means. Is it x^2+y^2+z^2? Gotta help me out here.
*January 23, 2015*

**Cgs**

x(t) = 9t - 1/3 t^3 + c since x(1)=2, 2 = 9 - 1/3 + c c = -20/3 x(t) = 9t - 1/3 t^3 - 20/3 when v=0, the particle has changed direction. That is when t=3. So, now just evaluate x(3).
*January 23, 2015*

**Math**

if you add the two equations, you get 5x = 20 I think you can solve that, eh?
*January 23, 2015*

**Relative Extrema: AP Calculus**

f = (3/4)x^4-x^3-3x^2+6x f' = 3x^3-3x^2-6x+6 f" = 9x^2-6x-6 extrema where f'=0 and f"≠0 f increasing where f' > 0 there are two inflection points because f" has two real roots.
*January 22, 2015*

**Antiderivatives**

Close, but no cigar. For powers, raise it by one and divide by it. So, F(x) = 1/6 x^6 -4(1/-2) x^-2 - 4x + c = 1/6 x^6 + 2x^-2 - 4x + c Since F(1) = 1, 1 = 1/6 + 2 - 4 + c c = 17/6 F(x) = 1/6 x^6 + 2x^-2 - 4x + 17/6 Frankly, I think the negative exponent is a typo, but that&#...
*January 22, 2015*

**Math**

You find out your faucet is leaking 10 pints of water every 3 hours. After 6 hours, how many gallons of water will have leaked from the faucet? How do I solve this problem?
*January 22, 2015*

**Math**

5-2*(6-(4+2))=5 Still thinkin' on the other one
*January 22, 2015*

**help math algebra**

for addition and subtraction, just collect terms with the same power (7a^5-a^3)-(a^5-5a^3-1) 7a^5-a^3-a^5+5a^3+1) (7-1)a^5 + (-1+5)a^3 + 1 4a^5 + 4a^3 + 1 When multiplying, use the distributive property (5x-3)(x^3-5x+2) (5x)(x^3-5x+2) - 3(x^3-5x+2) 5x^4-25x^2+10x-3x^3+15x-6 5x...
*January 22, 2015*

**Math**

1.50n + 2.00+1.25n
*January 22, 2015*

**Math**

standard form does not involve an intercept. The standard form for a line is Ax + By = C You have done it correctly. And, the intercept was given. It is zero.
*January 22, 2015*

**geometry**

has 5 sides of length 9 ft each
*January 22, 2015*

**geometry**

KL/JL = tan 24° you know KL, so now just solve for JL.
*January 22, 2015*

**Algebra 1**

Thank you
*January 22, 2015*

**Algebra 1**

Does the table represent an expoential function? x 1 2 3 4 y -1 -8 -27 -64 yes or no my answer is no
*January 22, 2015*

**math**

T5/T2 = r^3, so r^3 = (x^4/8)/(4x) = x^3/32 r = x/∛32 I suspect a typo, but we'll go with what we have. T10 = T5 r^5 = x^4/8 * x^5/(256∛2) = x^9/(2048∛2)
*January 22, 2015*

**Math**

It's good. You don't really need the leading "-" if you say a is negative, but having it there does signal your intentions clearly.
*January 22, 2015*

**College Algebra**

read the "trajectory" article at wikipedia.
*January 22, 2015*

**Math**

#1 is always true. Draw a triangle. Extend one side so that you can see the interior and exterior angles. They add up to a straight line (the extended side). Thus they are supplementary. #2 sometimes #3 never Have you tried drawing the triangles to illustrate the ideas?
*January 22, 2015*

**hw dump**

I've done a couple. How abut you show some work of your own, rather than just doing a homework dump?
*January 22, 2015*

**math**

2x+(3x-(4x-5))=x/4-2 2x+(3x-4x+5)=x/4-2 2x+(-x+5) = x/4 - 2 x+5 = x/4 - 2 3x/4 = -7 x = -28/3
*January 22, 2015*

**math - bogus**

x^2 + y^2 = 20 xy = 192(39.37^2) = 297600 Clearly x and y are less than 20. No way could their product be so huge. I suspect a typo.
*January 22, 2015*

**math**

The nth row has 35-4(n-1) = 39-4n plants. So, what is the largest multiple of 4 less than 39? Subtract that from 39. Or, just divide 39 by 4. The remainder is how many plants are in the last row. It is the row that is too short to subtract 4 from it again.
*January 22, 2015*

**calculus**

v(t) = ds/dt = 50-4t find t when v=0
*January 22, 2015*

**math**

.99(1.05)
*January 22, 2015*

**Geometry**

If the longer ladder is x, and reaches up y feet on the wall, then 8.3^2 + y^2 = x^2 8.3^2 + (y-9.1)^2 = (x-7.2)^2 x = 17.9
*January 22, 2015*

**Geometry**

a general circle is (x-h)^2 + (y-k)^2 = r^2 since the center is on y=2x+1, k=2h+1 (x-h)^2 + (y-2h-1)^2 = r^2 Since the circle passes through (4,5), (4-h)^2 + (5-2h-1)^2 = r^2 Since the circle is tangent to the y-axis, h=r, so (4-r)^2 + (4-2r)^2 = r^2 r = 2 or 4 You can now ...
*January 22, 2015*

**Math-please help**

If there are x seats at $5, then income = 5x + 9(500-x) expenses = 4000 profit = income - expenses
*January 21, 2015*

**Math**

Since c = 2pi r, r = c/2pi a = pi r^2 = pi(c/2pi)^2 = c^2/4pi so, plug in your value for c.
*January 21, 2015*

**math**

2/3 = 16/x x = 24
*January 21, 2015*

**math**

The ratio is clearly 24:5. So, QR:10 = 24:5 45:FG = 24:5
*January 21, 2015*

**Math**

94+67+83+93 = 337 5*90 = 450 Looks like she needed a 113 on the final test. I suspect a typo. Fix it and redo the math.
*January 21, 2015*

**Math please help**

(1/3 mi)/(1/15 hr) = 5 mi/hr (1/5 mi)/(1/30 hr) = 6 mi/hr I suspect you can finish it off from here, eh?
*January 21, 2015*

**6th Grade Math**

Either way is right, but it looks like you're both wrong 6 3/8 + 2 1/16 = 8 7/16 8 7/16 + 4 3/4 = 13 3/16 He should have added the mixed numbers on the right, then subtracted the sum: 4 3/4 + 2 1/16 = 6 13/16 So, 6 3/8 = t - 6 13/16 6 3/8 + 6 13/16 = 13 3/16 Guess you'...
*January 21, 2015*

**Math**

.85*.87 + .15*.85 = .867 Sounds right, since the final score is just about the same as the average so far.
*January 21, 2015*

**Algebra 1**

My answer is 4.5 x 10^9
*January 21, 2015*

**Algebra 1**

What is the correct simplification of 5.4x 10^12/ 1.2x 10^3 written in scientific notation?
*January 21, 2015*

**math**

N = kA/P If A is doubled, so in N. So, (D)
*January 21, 2015*

**math**

f(x) = 15 + 4.24(x/120)
*January 21, 2015*

**Algebra 1**

thank you
*January 21, 2015*

**Algebra 1**

clearly, it's 36(6x^5)
*January 21, 2015*

**Algebra 1**

A fraction reduces to 36. If it's denominator is 6x^5,what is it's numerator?
*January 21, 2015*

**Math**

4^.5x = (4^.5)^x = 2^x This is easy to see, since log_4(x^2) = 2log_4(x) = log_2(x)
*January 21, 2015*

**Math**

36:(36+28+16) = 36:80 = ?
*January 21, 2015*

**precal**

5r + 3(r+4) = 52
*January 21, 2015*

**Physics**

when they act in the same direction.
*January 21, 2015*

**math**

it will travel 1km in 1km. If it takes 1000 hops, it will travel 2km It will take 500 hops to travel 1km.
*January 21, 2015*

**math**

(-2,12)
*January 21, 2015*

**Algebra II**

I don't think you really want a "z" floating around. I'll assume you meant a "2". The first two are just straightforward multiplication and division. You can surely do those. (g◦(h◦f))(-4) = g(h(f(-4)) = g(h(-2)) = g(9) = -33
*January 20, 2015*

**Calculus: Intergration**

This kind of stuff usually works best with a trig substitution. Note that 4x-x^2 = 4-(x-2)^2 So, let u = x-2 and you have du/(4-u^2)^(3/2) Now, let u = 2sinθ du = 2cosθ dθ 4-u^2 = 4-4sin^2θ = 4cos^2θ Now the integrand is 2cosθ dθ/8cos^3θ...
*January 20, 2015*

**Trig/Precalc #1**

If we call the two circles C1 and C2, respectively, then note that (2,1) lies on C2. So, the external tangents will be bisected by the line joining the two centers. Note that both circles are tangent to the x-axis. So, figure the slope of the line joining the two centers, and ...
*January 20, 2015*

**Pre-Calc**

This is just algebra I. You want x where -76x^3+4830x^2-320000 = 800000 I suggest a graphing utility, as this has no rational roots.
*January 20, 2015*

**Pre-Calc**

the circumference of the circle is 100-x. So, the area is a = (x/4)^2 + π((100-x)/2π)^2 This is just a parabola, so its vertex (minimum area) is easy to find. For the maximum area, compare a at the ends of the domain.
*January 20, 2015*

**Math**

2:3 = 18:x so, x=27, the no. of blue pens. Now, you have to decide the color(s) of the 3 pens removed to figure the new ratio.
*January 20, 2015*

**Pre-Calc**

the page is clearly 4" wider and higher than the print. That means that (x-4)(y-4) = 30 y-4 = 30/(x-4) y = 4+30/(x-4) The area A is xy, so A = x(4+30/(x-4)) = x(4(x-4)+30)/(x-4) = x(4x-16+30)/(x-4) = 2x(2x+7)/(x-4) I think the rest is fairly straightforward
*January 20, 2015*

**Math**

Piece of paper is 0.0075 inch thick. How many sheets of paper will be in a stack that is 2.25 inches high?
*January 20, 2015*

**Math**

Please help!!!!!!!!!!!!!
*January 20, 2015*

**Math**

First week sells 6 chairs for $80 each. Next week, if chair is not sold, it will sell for 0.85 times previous week's price. Store needs to sell 6 chairs for total of $270 to make a profit. what is the last week in which all 6 chairs could be sold so that the store makes a ...
*January 20, 2015*

**Science**

s = vt - 1/2 at^2 20t - 1/2 at^2 = 100 Also, v = Vo-at, so 20-at = 0 at = 20 so, 20t - 1/2(20)t = 100 t=10 So, a = 2 F = ma = 800*2 = 1600N
*January 20, 2015*

**Coll Algebra**

If the short side is x, then x + 2x + 2x = 30
*January 20, 2015*

**Math**

In a way. To say that the single equation on the left is the "same" as the two other equations is not technically true, but it does have the same solutions as the others. Actually, there is no value of x such that x=0 and x+6=0. x(x+6) = 0 is true if x=0 OR if x+6=0...
*January 20, 2015*

**physics**

F = ma You have m and a.
*January 20, 2015*

**algebra**

add the exponents of all the variables in each term. The degrees can be easily seen to be 4, 5, 5, 0 The degree of the polynomial is the highest degree among the terms. In this case, 5.
*January 20, 2015*

**Math**

No. In 1 minute, 1/20 of the tub fills, while 1/15 drains. So, the net rate of filling is 1/20 - 1/15 = -1/60 So, in 60 minutes the full tub drains. This assumes, of course, that the drain is opened when the tub is completely full.
*January 20, 2015*

**Math-Polynomials/Zeros**

if you're talking about quadratics with no constant term, then they look like y = ax^2+bx That's just y = x(ax+b) and it has two real roots (0 and -b/a). No complex roots are possible.
*January 20, 2015*

**Math**

what, no ideas? Check the discriminant. ax^2+bx+c has only complex roots if b^2-4ac < 0
*January 19, 2015*

**Math**

I gotta think you meant f(x) = x^4-4x^2+k we know that x^4-4x^2 = x^2(x^2-4) = x^2(x-2)(x+2) so it has 3 real roots, one repeated. x^4-4x^2+4 = (x^2-4)^2 = (x-2)^2(x+2)^2 so it has 4 real roots (2 distinct) x^4-4x^2+k has 4 distinct real roots if 0 < k < 4 x^4-4x^2+k has...
*January 19, 2015*

**math**

incorrect. |x| is never negative.
*January 19, 2015*

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