Saturday

April 25, 2015

April 25, 2015

Total # Posts: 30,783

**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*

**Physical Science**

(12/120) * 500
*April 4, 2015*

**Physics**

I think you might get a clearer picture of the situation by reading the discussion here: http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/earthole.html
*April 4, 2015*

**math - incomplete**

42
*April 4, 2015*

**Consumer Math**

correct
*April 3, 2015*

**Algebra 2**

pick any value for x, say 20 Then 2*20+y = 8 40+y = 8 y = -32 So, (20,-32) is one pair Or, pick any value for y, say 0 Then 2x+0=8 x=4 So, (4,0) is another pair
*April 3, 2015*

**Math**

if the circumference is 1/40 as big, then so is the diameter.
*April 3, 2015*

**Physics**

If the amplitude is A, then it goes from -A to +A, or a distance of 2A. But during one period, it goes up and back again, for a distance of 4A.
*April 3, 2015*

**geometry**

or, you can use a compound inequality. 34-22 < x < 34+22 12 < x < 56
*April 3, 2015*

**Geometry**

correct
*April 3, 2015*

**Geometry**

A pilot sees a guy at an angle of depression of 50 degrees. If the pilot is 200 degrees from the guy, how high is the pilot? Would it be sin(50) x 200?
*April 3, 2015*

**pre calculus**

oops (b) [100*20 + x(20-5)]/(100+x)
*April 3, 2015*

**pre calculus**

(a) ?? unless the pricing varies somehow the cost for x skiers will always be the same (b) [100*20 + x(20-5)]/x ...
*April 3, 2015*

**PHYSICS**

If the parts are x and M-x, then F = Gx(M-x)/r^2 = G/r^2 (Mx-x^2) This is just a parabola, with vertex at M/2. That is, the force is maximum when the masses are equal. It's like the area of a rectangle with constant perimeter is greatest if it is a square.
*April 3, 2015*

**Math**

if x sell at $40, then the rest (6000-x) are $26, so 40x + 26(6000-x) = 190500
*April 3, 2015*

**Geometry**

the slope of AB is -5/3 so, which if the choices has that same slope?
*April 3, 2015*

**math**

try using a common denominator again. Then pick the smallest one.
*April 3, 2015*

**m ath**

2^-2 = 1/2^2 = 1/4
*April 3, 2015*

**math**

rewrite them all with denominator of 8: 4/8 5/8 7/8 6/6 now just sort them by numerator.
*April 3, 2015*

**Calculus**

if xi is the right endpoint, then 3 cannot be x1. That leaves only c and d for choices. Since the interval length is 2, and the number of divisions is 4, each interval is .5 in width. Looks like (c) to me. BTW, (d) is the set of midpoints.
*April 3, 2015*

**Math**

thank you
*April 3, 2015*

**Math**

If I know all 3 angles of a right triangle and the hypotenuse how do I figure out the short side length of the triangle?
*April 3, 2015*

**6th Grade Math ASAP!!!**

you're right -- it is complex. Especially so since you don't seem to have any questions about it.
*April 3, 2015*

**Math**

rotation through 180° changes both signs. So, (3,-5) -> (-3,5) Did you actually plot your solution? You would see that it was nowhere near the rotated point. an equilateral triangle has axial and rotational symmetry.
*April 3, 2015*