Wednesday

May 27, 2015

May 27, 2015

Total # Posts: 31,408

**Algebra 1**

well, since they are usually written as y = a * b^x it seems pretty clear, wouldn't you say?
*April 8, 2015*

**physics**

If the first object takes t seconds to hit, h - 4.9t^2 = 0 t = √(h/4.9) the second object is thus h-4.9(t-1)^2 = 20 h = 31.63 m
*April 8, 2015*

**Math**

Thomas put 1/4 of the c coins he had in his pocket into the jar under his bed. He put 16 coins into the jar. The equation that models this situation is 1/4c = 16. How many coins did Thomas have in his pocket? a 4 coins b 12 coins c 20 coins d 64 coins The answer would be c.
*April 8, 2015*

**AP CALC**

since x^2+y^2+z^2 = 4 using symmetry, we can take 8 times the volume in the first octant. Then v = 8∫[0,2] ∫[0,√(4-x^2)] ∫[0,√(4-x^2-y^2)] dz dy dx
*April 8, 2015*

**Math**

no. rays might be parallel such an angle of zero measure could be said to fit the constraints, but that might not be allowed.
*April 8, 2015*

**calculus**

assuming an open box, then x^2 + 4xz = 426 v = x^2 z = x^2 (426-x^2)/4x = 426x - x^3
*April 8, 2015*

**Math didn't post problem right**

find the Quotient: 1,754/21 a 1733 b 21 11/83 c 83 11/21 d 1775 Is C the correct answer. I had post the problem wrong. Sorry
*April 8, 2015*

**Math**

find the quotient: 1,754/12 a 1733 b 21 11/83 c 83 11/21 d 1775 Would C be the correct answer?
*April 8, 2015*

**Math**

I agree.
*April 8, 2015*

**Math**

The determinant |2 6| |1 3| = 6-6 = 0 So, there is no inverse
*April 8, 2015*

**Algebra**

Better think again, S. the line x=4 is a vertical line The vertical line through (-6,-2) is x = -6
*April 8, 2015*

**Algebra 2 math**

the triangle's 3rd side is √(41^2-40^2) = 9 So, now you know all three sides, and the angles, so the trig functions are easy to read off. sin G = 9/41 and so on
*April 8, 2015*

**linear algebra-urgent**

you know p. Can you not figure its length? √(33^2+44^2) = 55
*April 8, 2015*

**linear algebra-urgent**

#1 a unit vector in the direction of w is z=[3/5;4/5] p = u.z = 11/5 z = [33/25;44/25] = [1.32;1.76] you are correct |kp| = k|p| = 55/25 k So, k = 25/55 As for the span, that is usually defined for a set of vectors. span{w} would just be w. So, any vector orthogonal to w will ...
*April 8, 2015*

**math**

54.2/16 * 2.31
*April 8, 2015*

**math**

Not even close. The area is length * width, or 8(6x+3) = 48x+24 6x+3 is not 9x. Even if it were, 9x+8 would be half of the perimeter, not the area.
*April 8, 2015*

**Geometry**

wrong. The two circular ends of the cylinder are usually parallel. I guess that leaves only one other possibility, right?
*April 8, 2015*

**math**

well, just start listing them: 3568 3586 ... 8653 There are only 24 of them.
*April 8, 2015*

**Algebra**

If Nathan is x and Nicole is y, we have y = 2/3 x (y-2) = 1/2 (x+5) Now just solve for x.
*April 8, 2015*

**Math (Please help ASAP)**

It's just a quadratic in p: q+p^2-33p = 9 p^2 - 33p + (q-9) = 0 Now just use the quadratic formula to get the two values for p.
*April 8, 2015*

**Math**

1/3 (9x-2) + 1 = 2(4x+1) You can multiply by 3 to get 9x-2 + 3 = 6(4x+1) 9x+1 = 24x+6 -5 = 15x x = -1/3
*April 8, 2015*

**chemistry**

CuS + 2HNO3 = Cu(NO3)2 + H2S That should help, right?
*April 8, 2015*

**trigonometry**

speed = distance/time, so 2π*3960mi/24hr = ? mi/hr 2πrad/24hr = ? rad/hr
*April 8, 2015*

**trigonometry**

v = 2π*14in/rev * (.5/2π)rev/s = 28 in/s .5rad/s * 1rev/2πrad * 60s/min = 4.77 rev/min .5rad/s * 180°/πrad = 90/π °/s
*April 8, 2015*

**maths**

this is just an A.P. with d = 4 a = 100-20*4 = 20 So, the sum of 21 rows is S = 21/2 (20+100)
*April 8, 2015*

**math**

draw your triangle the other side is √15 since we are in QII and sin is positive, x = -√15 y = 1 r = 4 so, cosx = -√15/4 Now use those values to plug into your half-angle formulas.
*April 8, 2015*

**Pre-calc**

Or, you can go the other way sin(7x) = sin(6x)cos(x) + cos(6x)sin(x) and start expanding those as well, till all you have left is a bunch of sin(kx).
*April 7, 2015*

**Pre-calc**

http://www.wolframalpha.com/input/?i=%28sinx%29%5E7 will show the answer you need. sin^7 = sin(1-cos^2)^3 Now you can start expanding and using the sum formulas. I'm sure a google search will show up all the gory details.
*April 7, 2015*

**math**

why use } when / is available? (4/9)(1/8) = 1/18 (1/18)(1/3) = 1/54
*April 7, 2015*

**Math**

correct.
*April 7, 2015*

**Math**

There is clearly a typo in the above, since the function is a parabola which opens upward, and so has no maximum. If we go with y = -6x^2+42x-60 then that works out to y = -6(x^2-7x+10) = -6(x-5)(x-2) The vertex is at x = 3.5, so that means 3500 boards. You know, if you keep ...
*April 7, 2015*

**Math**

-5x^2 - 30.5x = -1/10 (50x^2 - 305x) = -5/10 x (10x-61) I suspect a typo, since the roots of the above are clearly 0 and 6.1
*April 7, 2015*

**Math**

no, it can be any real number.
*April 7, 2015*

**Calculus**

see the related questions below.
*April 7, 2015*

**math**

I'd think so, since the eye perceives the linear dimensions, which grow much more slowly than the volumes.
*April 7, 2015*

**I NEED HELP WITH THIS**

how far do you get? Do you not have any ideas? If not, you'd better review the textbook where it discusses this. To start, A series: R = r+r+r parallel: 1/R = 1/r + 1/r + 1/r
*April 7, 2015*

**grammar**

I agree with (a) I think if it had said each delegate and each alternate, then (b) would be better.
*April 7, 2015*

**math**

you ought to explain what "1 } 10" means.
*April 7, 2015*

**math**

P is the same as if there were a 5-section wheel with just the numbers 1-5.
*April 7, 2015*

**Math**

you mean you can figure out 2*3+5, but you cannot do the same for 1,2,4? Ai caramba!
*April 7, 2015*

**Algebra**

A: LW = √18√24 = √(18*24) = √(2*3^2 * 2^3*3) = √(2^4 3^3) = 12√3 since A = LW, what if you have (L/2)(W/2)?
*April 7, 2015*

**geometry**

without some kind of explanation of the angles and the diagram, I don't think you can get much help here. By the way, ≅ is congruent. Rather than describing the symbol, why not just say congruent? And your opening sentence is bogus, since you don't say what <1...
*April 7, 2015*

**math help**

F is undefined where the denominator is zero #2 ? #3 domain is all reals except for the undefined value(s) #4 y-intercept (at x=0): -6/(0-3) -1 = -6/-3 - 1 = 2-1 = 1 x-intercept (at y=0) -6/(x-3)-1 = 0 -6 - (x-3) = 0 -6-x+3 = 0 x = -3
*April 7, 2015*

**Math**

well, 12^2 = 144, so you want 6x+6 = 12 or 6x+6 = -12
*April 7, 2015*

**Math**

#1 √(x+4)-3 >= 4 √(x+4) >= 7 x+4 >= 49 x >= 53 #2 t = √(d/16), so we want (using t in seconds) √(d/16) > 60 d/16 > 3600 d > 57600
*April 7, 2015*

**Math**

(2w+a)^8 = ... + 16wa^7 + ... (-x+b)^7 = ... - 35x^3b^4 (y-2z)^4 = ... + 24y^2z^2 So, I get -13440wx^3y^2z^2
*April 7, 2015*

**science.......**

(a) 60W * 1 hr = 60 Wh (b) .060 kWh * .1745 $/kWh = 0.01 200kJ/270s = 740W
*April 7, 2015*

**math**

well, how many points in the empty set?
*April 7, 2015*

**UNISA**

to accrue to how much?
*April 7, 2015*

**math**

If I interpreted the rather garbled English, you want x and y where x+y = 44 xy = 1280
*April 7, 2015*

**math**

eliminate z and you have 100-x-y = 200-10x-2y 9x+y = 100 So, you could let x=10, y=10, that would make z=80 Or, you could have x=1,y=91, so z=8 There is no unique solution.
*April 7, 2015*

**algebra**

I think you need some parentheses in that horrid run-on expression. As written it could mean x^2 - 9y^2/xy / 1/y - 3/x = x^2 - 9y/x * y/1 - 3/x = x^2 - 9y^2/x - 3/x = x^2 - 3(3y^2+1)/x There are, of course, many other ways to parse all that stuffed jammed together. Unless ...
*April 7, 2015*

**science 1 question**

ahem. it does not form energy by spinning. It changes electrical energy into kinetic energy (of motion).
*April 6, 2015*

**science 1 question**

do you feel sucked into the fan when you turn it on? Does it feel like when an elevator starts? That's gravitational. Hint: what the heck does a fan do when you turn it on?
*April 6, 2015*

**Math**

well, ya got a table? Maybe these graphs will help you out in determining the transformations required. http://www.wolframalpha.com/input/?i=plot+y%3D3%5Ex%2C+y%3D3%5E%28%E2%88%92%28x%2B1%29%29+%E2%88%922
*April 6, 2015*

**Calculus**

Just curious. How do you get from 2(2)dy/dt+(2)(-1)(-4)+6(-1)^2=0 to 10 dy/dt+8=0 ???
*April 6, 2015*

**Calculus**

Assuming you mean c^2 = x^2 + 98√(x+57) then c^2(4) = 4^2 + 98√61 = 16+98√61 c(4) = 27.95 2c dc/dx = 2x + 49/√(x+57) at x=4, we have 55.90 dc/dx = 8+49/√61 dc/dx = 0.255 Of course, I might have misread the function, with all those pesky words ...
*April 6, 2015*

**Chemistry**

(a) you are diluting the concentration by a factor of 6/.25=24 So, you will need 20/24 ml of 6M solution to produce 20ml of .25M solution. The rest, of course, is water. Do the others in like wise.
*April 6, 2015*

**Calculus**

Hmm. Ignore my previous comment. Still, if the functions are as given, Reiny's answer appears correct. Are there mis-types somewhere?
*April 6, 2015*

**Calculus**

well, what is P? That is the rate you are calculating.
*April 6, 2015*

**1 question omh help??**

Looks like C to me.
*April 6, 2015*

**intermediate algebra**

Hmm. I get (3(x-3) - x(x+3) + 1(x-3)(x-3)) / ((x-3)(x-3)(x+3))
*April 6, 2015*

**Physics**

momentum must be conserved: 1*3 + 2*0 = (1+2)v Although, I fail to see how they could properly roll, if sticking together after such a collision.
*April 6, 2015*

**Physics**

assuming the original mass was really 20.0 kg, total momentum must remain at zero, so 15.0*2 + 5.0v = 0
*April 6, 2015*

**Pre-Calculus**

not quite. since (x+a)^2 = x^2+2ax+a^2, x^2+9x = x^2+9x+(9/2)^2-(9/2)^2 x^2+9x+20 = (x + 9/2)^2 + 20-81/4 = (x + 9/2)^2 + 319/4
*April 6, 2015*

**calc**

f = 2x+15-19e^x f' = 2-19e^x f'(0) = 2-19 = -17 so, the tangent line is y+4 = -17(x-0) see the graphs at http://www.wolframalpha.com/input/?i=plot+y%3D2x%2B15-19e%5Ex%2C+y%3D-17x-4
*April 6, 2015*

**calc**

x = e^(8-p) revenue is x*p = pe^(8-p) profit = revenue-cost = xp-x = x(p-1) = (p-1)e^(8-p) so, if y is the profit at price p, dy/dp = (2-p)e^(8-p) set the price at p=2
*April 6, 2015*

**chemistry**

if you mean g/L, that would be 1mole/22.4L = 0.759 g/L
*April 6, 2015*

**Calculus**

well, geez, just plug in e^2 into f'(x) f'(e^2) = 4(ln(e^2))^3/e^2 = 4(2)^3/e^2 = 32/e^2 remember ln(e^u) = u e^(ln u) = u
*April 6, 2015*

**algebra**

what is that 4 doing there? is 4√y supposed to mean 4th root of y? x^(11/10) is 10th-root(x^11)
*April 6, 2015*

**math**

man, look up your point-slope formula: y-5 = 2/3 (x+1)
*April 6, 2015*

**geometry**

transitive: A≅B and B≅C ==> A≅C No idea what the diagram shows.
*April 6, 2015*

**geometry**

M=(A+B)/2 clearly AM=MB = 1/2 AB Look up your distance formula to figure length of AB.
*April 6, 2015*

**Calculus 2 (Series)**

see the solution here: http://www.math.ucla.edu/~hendricks/CalculusIISummer2011/calc2practicefinalsolutions.pdf
*April 6, 2015*

**math**

5f+4s = 14.80 (3/4)f = (3/5)s s = 1.85
*April 6, 2015*

**maths**

before: TTT after: TTT TTT so, how many T's?
*April 6, 2015*

**Differential Equation 4**

no ideas on these problems? Homework dumps are discouraged.
*April 6, 2015*

**Differential Equation 3**

why the stupid carets? These are not exponents. (x^2+1)y"+2xy'=0 Since y = c1 + c2 arctan(x) I suspect you can now come up with the series.
*April 6, 2015*

**algebra**

that copy/paste stuff will kill ya every time!
*April 6, 2015*

**calculus**

v(t) = ds/dt = 128-32t So, plug in t=4.
*April 6, 2015*

**math**

for m months, the cost c is c = 127 + 28m now plug in m=9 for the cost of 9 months. actually, c is the cost of joining and then using the club. The question is poorly worded.
*April 6, 2015*

**Precal**

so, if u=3^x, you have u^2 - 4u + 3 = 0 You can handle that, I presume?
*April 6, 2015*

**calculus**

wrong h = 130 + 35t - 16t^2
*April 6, 2015*

**ET 1210 FUNDAMENTALS**

E/R -> (2E)/R = 2E/R
*April 6, 2015*

**ET1210 DC/AC FUNDAMENTALS**

I=E/R so, the new I will be E/(R/2) = 2E/R
*April 6, 2015*

**math**

since the speed is the same, 7/60 = x/24
*April 6, 2015*

**Physics**

well, what was the date 250 years ago? A light-year is the distance light travels in a year. So, it took the light 250 years to get to earth.
*April 6, 2015*

**Precal**

Dan and Reiny just did one of these for you. Just make sure everything is expressed as powers of 3, then equate the powers to solve for x.
*April 5, 2015*

**physics**

momentum is mv surely you can figure the starting and ending values. The time taken makes no difference.
*April 5, 2015*

**math**

the slope is the constant of variation. In this case, 11. This is just a special case of the slope-intercept form y = mx+b where b=0.
*April 5, 2015*

**PHYSICS**

work = force * distance so, how far does it travel in 1 second? F=ma, so a=F/m s = 1/2 at^2 = 1/2 (F/m) t^2
*April 5, 2015*

**Precal**

Since 25 > 21, the ellipse is long on the y-axis. So, the vertices are (0,5) and (0,-5) You should have immediately seen your answers were incompatible. The foci must lie on the major axis. Your foci are correct.
*April 5, 2015*

**Math**

12000(1+.08/4)^(4*4) = 16473.43 900*(1.02^16+1.02^15+...+1.02^1) = 900(1.02^16 - 1)/(1.02-1) = 16775.36 Have I missed something? My answers are about 1/2 the expected values.
*April 5, 2015*

**AP CALC**

#1. solve for t in 0.985^t = 0.8 #2 dy/dx = 3√x √y dy/√y = 3√x dx 2√y = 2x^(3/2) + c at (1,4) we have 2√4 = 2*1^(3/2)+c 4 = 2+c c = 2 2√y = 2x^(3/2)+2 at x=0, 2√y = 2 y = 1 check: y = (x^(3/2)+1)^2 y' = 2(x^(3/2)+1)(3/2 &#...
*April 5, 2015*

**trig**

since sin^2 + cos^2 = 1, cos(23) = √(1-p^2) cos(113) = cos(23+90) = cos(23)cos(90) - sin(23)sin(90) = -p sin(46) = 2sin(23)cos(23) = 2p√(1-p^2) Time to review your basic sum/double-angle formulas
*April 5, 2015*

**maths**

sin(2x) = 1/2 tan(x) 2sinx cosx = 1/2 sinx/cosx 4sinx cosx = sinx/cosx Clearly, sinx=0 is one intersection Elsewhere, we can divide through by sinx, and we have 4cos^2x = 1 cosx = ±1/2 Now you can easily find the points you want.
*April 5, 2015*

**Math**

what? You can't take a number, multiply it by -2 and subtract 4? y(0) = -2*0-4 = -4 Clearly, only C and D are possible answers. Now find y(1) the same way and you should get the correct choice.
*April 5, 2015*

**algebra**

If the sons are age a and b, with a<b, f+a+b = 50 f-4 = 8(b-4) f+4 = 4(a+4)
*April 5, 2015*

**Geometry help**

if the perimeter is p and the apothem is a, then the area is 1/2 ap #1. correct: 12/√2 #2. hint: the triangle's altitude is 18. #3. side is 12
*April 4, 2015*

**Differential Equation 1**

well, the solution of the homogeneous equations is y = c1 cos(2lnx) + c2 sin(2lnx) + c3/x^2 Not sure what to do with the t's, though.
*April 4, 2015*