Friday

April 25, 2014

April 25, 2014

Total # Posts: 21,980

**math**

4 s's out of 11 letters, so ...

**math**

what are the odds i favor of picking an S in Mississippi?

**Algebra II**

draw the lines for the equations For the first one, shade the area below the (dashed) line, since y is less than 2x-9 For the second one, shade the area above the (solid) line, since y is greater than or equal to 3-5x.

**Physics**

v = Vo + at s = Vo*t + 1/2 at^2 12 = Vo + 10a a = (12-Vo)/10 100 = Vo*10 + (12-Vo)/20 * 100 100 = 10Vo + 5(12-Vo) 100 = 5Vo + 60 Vo = 8

**algebra 2**

just substitute: 16x^2 - 96x + 5(16x^2-64) = 256 16x^2 - 96x + 80x^2 - 320 = 256 96x^2 - 96x - 576 = 0 x^2 - x - 6 = 0 (x+2)(x-3) = 0 Now you have x, get y. see the solution at http://www.wolframalpha.com/input/?i=solve+16x^2-5y^2%3D64%2C+16x^2%2B25y^2-96x%3D256

**maths**

a^2 + b^2 = 16 2ab = 8 (a+b)^2 = 24 so, a and b will not be integers. Their sum is √24 or -√24, and both will have the same sign, since ab > 0. b = 4/a, so we have a^2 + 16/a^2 = 16 a^4 - 16a^2 + 16 = 0 a = ±2√(2±√3) b = ±(√...

**math**

the garden is 10x10, so what's the perimeter?

**math**

correct. The power set of A P(A) is the set of all subsets of A. These would be {}, {2}, {3},...{2,3},{2,5},... and so on up to A itself.

**math**

well, how many elements in A?

**Algebra II**

Since speed * time = distance, we have (with jet=j and wind=w): 7(j-w) = 3220 3(j+w) = 2820 j=700 w=240

**algebra**

y = 6.2x + b 2222.4 = 6.2*52 + b, so b = 1900 So, we now know that y = 6.2x + 1900 Just plug in x=26 Or, without even finding b, we know that each gallon of fuel weighs 6.2 pounds, so just subtract 26*6.2 from 2222.4

**Astronomy**

since arc length s = rθ, just plug in the numbers: 7.4*10^3 * 6.3 * 1/3600 * pi/180 = 0.226 Kpc

**calcules**

elasticity e = df/f ÷ dp/p = df/dp * p/f df/dp = A(-0.13)p^(-1.13) so, e = -0.13Ap^(-1.13) * p/A p^(-0.13) = -0.13/p^0.26 so, we have negative elasticity, meaning that demand will go down if price goes up. It also shows that for larger prices, the elasticity changes, be...

**Math**

a=b b+2b = 6(a-26) 3b = 6(b-26) 3b = 6b - 156 b = 52 So, they both started out with 52 cupcakes.

**mathematics**

the distance from (-2,4) to the line 2x-3y-10 = 0 is 2√13, so that's the radius of the circle. (x+2)^2 + (y-4)^2 = 52 you can see this at http://www.wolframalpha.com/input/?i=plot+%28x%2B2%29^2+%2B+%28y-4%29^2+%3D+52+and+2x-3y%3D10

**math**

six sides, so make sure there are 2 odd numbers.

**math**

$10 is tax. 50% of that is $5, so reduce the cost by that much. What % of 90 is 5? Just wondering -- where is the profit needed to make money?

**math**

a < c a+c = 29 m = a+26 we want maximum value for alvin, because that will also give the max to melvin. Since a<c, alvin has to have less than half of their shared 29. So, a <= 14 a=14 c=15 m=40 max total: 69

**math**

a+50 = 2b b+50 = 2a (a+b)+100 = 2(a+b) a+b = 100

**math**

center at (0,0) a^2+b^2 = c^2 c = √85

**Calculus Help Please!!!**

well, f(x) is only defined on 0 <= x <= 1 Visit http://rechneronline.de/function-graphs/ and enter 8x*sqr(x-x^2) for your function. Set the range of y to be 2.5 to 3 and the peak will be quite clear

**Calculus Help Please!!!**

f(x) is differentiable on the interval. So, you know there is a c such that f'(c) = (f(2)-f(0)/(2-0) = (-1-2)/2 = -3/2 So, just solve for c in 4c-5 = -3/2 c = 7/8 as a check, view http://www.wolframalpha.com/input/?i=plot+y+%3D+2x^2-5x%2B1+and+y+%3D+%28-3%2F2%29%28x-7%2F8%...

**Algebra**

so, if you have √(y+3) - 4 = 5 √(y+3) = 9 y+3 = 81 y = 78 by the way, I meant that you could have written sqrt(y+3), not just show ... as the argument.

**Algebra**

try √ to copy/paste. as written, I read y+3-4 = √5 but that seems unlikely. You can also write sqrt(...) to show explicitly what is inside the radical.

**algebra**

after the nth year, it is worth 1000(1+.06)^n

**Algebra II**

well, r^2 = 4785^2+1140^2, so the circle's radius is 4919 feet. x^2+y^2 = 4949^2 Now just use your knowledge of the areas of circles and squares to answer the questions.

**Algebra Question~!**

just solve for h=0. -16t^2 + 200 = 0 16t^2 = 200 t^2 = 25/2 . . .

**geometry**

Draw a diagram, showing the altitude. Consider the sine of 1/2 the vertex angle. Its opposite side is half the base, and its hypotenuse is the slanting side. So, sin(θ/2) = 14/22

**geometry**

as with any quadrilateral, you get a parallelogram. This topic is discussed here: http://jwilson.coe.uga.edu/EMT669/Student.Folders/Dozier.Cynthia/essay1/Essay.html

**calculus**

max area for a given perimeter is a circle. Is the wire evenly divided? If so, c = p/2, so r = p/4π, and the total area is a = 2(πr^2) = 2π(p^2/16π^2) = p^2/8π If not, then if we have a tiny circle, (area effectively zero), then r = p/2π and a = &...

**college math**

1 - .85^5

**Calculus**

Looks good to me. I get ∫[1,2] (3-x) - 2/x dx = 3x - 1/2 x^2 - 2logx [1,2] = 3/2 - 2log2 gotta be a typo in the answer. 2log2 is correct.

**arithmetic**

oops. That would be 4,8,12,...

**arithmetic**

1,4,8,...

**math**

35 44

**algebra**

h(t)=0 when t = 1.5

**Programing**

I see a bunch of syntax errors, and no reference to cin >> x[i]. Before trying to debug your logic, make sure to get it to compile.

**Programing**

what's with the cout? you need x2[i][j] = x1[i][j] i goes from 0..2 and so does j. x1 and x2 are the arrays, not the bounds on i and j.

**Algebra**

2√(5L) = 60 √(5L) = 30 5L = 900 L = 180

**Physical Science 9**

what sequence of process must happen for an atom of carbon to go from a man to a car?

**math**

15(3 1/5) = 15*3 + 15*(1/5) = 45 + 3 = 48

**math**

If I pay, I don't get paid nothin'.

**Math**

y = a/c because as x gets huge, only x^2 matters. y = (a + b/x^2)/(c + d/x^2) as x gets huge, the fractions go to zero.

**geometry**

10^6 * 4/3 pi (.005^3) * 2 = pi/3 = 1.047 m^3

**Math**

#1 - forget about the blue pencils. There are 8 yellows in each package. So, in 426 packages, there are 8*426=3408. Note that the title of the problem set was "Multiply a 3- digit number by a 1- digit number". That should have been a clue that your approach was wrong...

**math**

well, yes, as I said. So, just work it out: 600 mi * 5280ft/mi * 12in/ft = 38,016,000 in Note how the units cancel, leaving you with just inches.

**math**

you know the circumference of the tire is 24pi or 75.4 inches. So, figure out how many inches there are in 600 miles, and divide that by 75.4 That's how many times the tire went around.

**Algebra**

you can get excellent graphing help here: http://rechneronline.de/function-graphs/ but you need to enter functions of x. So, solving for y, you have y = (5x+36)/3 y = (26-3x)/5 Enter those two functions and set the range on the y-axis to -10:10 and you will see the solution.

**Calculus**

Good idea. However, in an attempt to use your math, and also to apply to a possibly more general problem later, try implicit differentiation: x^2 + y^2 = 18 2x + 2yy' = 0 y' = -x/y So, if -x/y = 1 and x^2+y^2 = 18, 2x^2 = 18 x = ±3 Now, figuring y should not be ...

**Calculus: Integral**

recall that sec^2 = 1+tan^2, so you have ∫sec^4(4x) dx = ∫sec^2(4x)(1 + tan^2(4x)) dx = ∫sec^2(4x) dx + ∫tan^2(4x) sec^2(4x) dx = 1/4 tan(4x) + (1/4)(1/3) tan^3(4x) and you can massage that in several ways.

**math**

Glad to help. Translating words into symbols can be tricky, but the key is just to examine the data carefully. Believe it or not, it gets easier with practice, just like everything else.

**math**

2w + b = 36 2w + 2b = 56 well, since she walks 2 hours in each case, it is clear that the extra hour of biking gave her an extra 20 km. b = 20 so, since 2w+20=36, w=8

**algebra**

the amount of alcohol in the parts must add up to the whole. So, .3 * (8-x) + 1.0 * x = .5*8 x = 16/7

**Calculus Help Please!!!**

looks good to me

**Calculus Help Please!!!**

v = 4/3 pi r^3 dv = 4 pi r^2 dr c = 2pi r dc = 2pi dr so, dr = dc/(2pi) meaning that dv = 4 pi r^2 dc/(2pi) = 2 r^2 dr so, using the given numbers, dv = 2*(80/2pi)^2 * 0.5 = 1600/pi^2

**Calculus Help**

v = 2/3 pi r^3 (half a sphere) dv = 2 pi r^2 dr now just plug in the given r and dr watch the units.

**physics**

F = GmM/r^2 2.5*10^-10 = 6.674*10^-11 * x(4-x) / .25^2 x = 0.059 4-x = 3.941 Must be a bowling ball and a ping pong ball

**Algebra**

5m+3v = 29 2m+12v = 71 or 20m+12v = 116 2m+12v = 71 18m = 45 m = 2.50 v = 5.50

**math**

9x/4 = 1/3 x = 4/27

**Calculus Help Please!!!**

looking at a diagram, if A is a away from Q and B is b away from Q, then √(a^2+144) + √(b^2+144) = 39 a/√(a^2+144) da/dt + b/√(b^2+144) db/dt = 0 Now just plug in da/dt = 3.5 a = 5 b = 23.065 (from 1st equation when a=5) and solve for db/dt

**Calculus Help Please!!!**

when the water has depth x, the cross-section is a trapezoid with bases 30 and 30+x. So the volume of water at depth x is v = (60+x)/2 * x * 500 cm^3 = 250x^2 + 15000x so, knowing that dv/dt = (500x + 15000) dx/dt just solve that for dx/dt when x=20

**algebra 2**

I think you meant -17 instead of -7. If that's true, then the difference between terms is 15. So, the 10th term is -62 + 9*15 = ?

**math**

perimeter is 2(12+16) = 56 side of square is thus 14. So, the area is ? Note that 12*16 = (14-2)(14+2)

**math**

After 9 cycles he has made 18 miles On day 10 he swims the last 7 miles.

**math**

√(1^2+3^2) = √10 = ?

**engineering**

986.8*10^-9 * (1 - .5^(50/3.69*10^3)) = 9.225*10^-9 kg

**THE PARTS OF SPEECH**

A is present progressive B is present perfect C is present D is present tense, but passive voice

**Math**

just subtract the smaller volume from the larger: 10*10*15 - 7*9*12 = ?

**math**

You're kidding, right? 11 capable graduates in the whole state? Anyway, just work it out: P(1) = .56 P(2) = .56*.56 = .56^2 ... P(11) = ?

**Math - incomplete**

depends on how many she already has made. If she has made n shots so far, then we need x such that .70n + 1.00x = .75(n+x)

**math**

Good logic, but I wonder about the .47 in light of P(college) = .56

**Trig**

y=0 is not the y-axis. And anyway, in the stated domain, x=pi is the axis of symmetry.

**Trig**

see the graphs here: http://www.wolframalpha.com/input/?i=plot+y%3Dcos2x+and+y%3D-2sinx However, it might be better to graph y = -cos2x, then the final graph would be easier to visualize: http://www.wolframalpha.com/input/?i=plot+y%3D+-cos2x+and+y%3D-2sinx%2C+y+%3D+-cos2x-2sin...

**Trig**

sinC/c = sinA/a

**Trig**

you have two solutions for tanA, one positive, one negative. So, there are two values for A, one in each QI, one in QII.

**Trig**

period = 1/freqeuncy

**math**

assuming y is in billions, c(y) = 200 + .6y c(8250) = 200 + .6(8250) = 5150 or, 5.2 trillion looks ok to me. (b) subtract their spending from their income.

**math**

oops a+3x = 50

**math**

If adam is a now, then a - 1/2 = 12 a = 12 1/2 a + x/2 = 2x 12 1/2 + x/2 = 2x 25 + x = 4x x = 25/3 check: 25/6 + 25/2 = 25(2/3) = 2 * 25/3 25/2 + 75/3 = 100

**math**

heck no. a pipe of half the diameter only has 1/4 the area. So, for a given speed of the water, only half the volume is obtained.

**To Steve**

You could have added a posting to the original question. Anyway, There are 3 red marbles out of 9 total, so on the first draw, P(red) = 3/9 = 1/3 Without replacement, there are now 2 of 8 reds, so P(red) = 2/8 = 1/4 P(red,red) = 1/3 * 1/4 = 1/12 With replacement, both draws ar...

**math - incomplete**

and the other method is ... ?

**Calculus**

when dy/du = u^½ what does y = ? Just a simple power rule substitution. dy/du = u^n y = u^(n+1) / (n+1) + C

**algebra**

I can't make out the inequality sign, but that really makes no difference to the solution y = (x-4)(x+2)/(x-3)(x+5) You know there are roots at -2 and 4, and asymptotes at -5 and 3. So, the graph will cross the x-axis at -2 and 4. When x < -5, all factors are negative, ...

**algebra**

ok. sounds good to me.

**algebra**

42

**Stats**

Well, it must be immediately obvious that .9715 is bogus. A score of 10 is more than a whole SD below the mean, so there is no way that P(x<10) > 1/2 When I plugged in the data, I got P(x<10) = 0.1357 Still not one of your choices. However, the closest is 0.3, since y...

**Physics**

Oops. I just gave the mass of the seesaw on each side. That must be multiplied by the distance of its center of mass: 20(d/4.5)(d/2)+14*1.4 = 20(1 - d/4.5)((4.5-d)/2) + 39L

**Physics**

so, the mass of the seesaw can be ignored, since it is uniformly distributed. Now for the loads and their moments. They must balance on both sides, so 14*1.4 = 39*L Simple, no? Actually, since I have no diagram, I can't say that the seesaw mass may be ignored. If the pivot...

**math**

MTθF: 6/5 hr Sat: 4/5 hr W 1/5 hr 4 * 6/5 + 4/5 + 1/5 = 29/5 = 5 4/5 hr

**math help**

#2 is ok, but not yet complete: x^2-1 = (x-1)(x+1)

**Math 20-3**

v = 1/3 pi (3.4^2) (2.8) m^3

**Algebra**

If Literature, history and French are your life loves, then algebra probably will not be a great part of your life. But, life consists of a wide variety of experiences, and I guarantee you that some basic math know-how (yes, even including algebra) will make things easier. So,...

**Algebra**

Only you will know that. It's actually surprising how often basic math skills come in handy. Other than that, the mental skills developed when solving problems are definitely useful later in life, no matter the field of endeavor. Now, if you plan to find a sugar daddy/mama...

**Algebra**

well, 2(v-6) = 2v-12 Guess that's not it, eh? How about (v+4)(v-3) You need to find two numbers of opposite sign, which multiply to -12 and add up to +1. On the last one, (m^2 + 2m + 1/ m^3 + 3m^2 + 3m +1 (m^2/m - 3m/3) unless you can factor the polynomials, there's no...

**Algebra**

Just as in the previous two posts, you need to factor the trinomials and then cancel factors which occur in the top and bottom. Have you no ideas at all on factoring these? Or multiplying by the GCD to clear fractions?

**Algebra**

the GCD is x(x+3)(x+1), so if you clear fractions you get 3(x+3)(x+1) + 6(x)(x+1) = 8(x)(x+3) 3x^2+12x+9 + 6x^2+6x = 8x^2+24x x^2 - 6x + 9 = 0 (x-3)(x-3) = 0 x = 3

**Algebra**

r^2 + 6r +8 = (r+2)(r+4) So, what you have is (r^2-7r+12) / (r+4) * (r+2)(r+4) / (r^2-7r+12) Now lots of stuff cancels out and you are left with just (r+2)

**Statistics**

you can do lots of Z table stuff here: http://davidmlane.com/hyperstat/z_table.html

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | **8** | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>