Monday

September 22, 2014

September 22, 2014

Total # Posts: 18,620

**Math**

12/28 = 3/7 n^2/n^4 = n^-2 m^4/m^3 = m^1 = m so 3 n^-2 m or 3 m ----- n^2
*April 26, 2014*

**Trig**

(x - x1) (x - x2) = 0 (x - 5 - isqrt2) (x -5 +isqrt2) =0 distributive property multiply x (x -5 +isqrt2) = x^2 -5 x + ix sqrt 2 -5 (x -5 +isqrt2)= -5 x +25 -5isqrt 2 -isqrt2(x -5 +isqrt2)=-xisqrt2+5isqrt2 +2 add = x^2 -10 x +27
*April 26, 2014*

**Trig**

You are welcome.
*April 26, 2014*

**Trig**

cos = 1/sec = 4/5 cos is positive in Quadrant 4, x is positive and hypotenuse is positive.
*April 26, 2014*

**Math**

Well, you really did not ask a question. All you did was give the equation fort a parabola. So what? y = x^2 - 2 x - 3 do you want to know where that is zero? Where the vertex is? how it looks? if you want the two zeros, just factor it y = (x-3)(x+1) that is zero when: x = 3 ...
*April 26, 2014*

**Science**

sometimes twin stars hold each other in orbit. Imagine the huge gravitational force !
*April 26, 2014*

**Science**

5 is D, close stars. Gravity force between stars is huge despite distance F = G M2 M2 / d^2 between A and B it would be A because same mass but closer (smaller d^2) 7 is B Train around bend is change in DIRECTION. velocity is vector, speed and DIRECTION 8 is A, size is not ...
*April 26, 2014*

**Science**

Oh ok I will check
*April 26, 2014*

**Science**

Hey, I already passed the course. You try to answer the questions and one of us might check and figure out what you are missing. We are not here to take the course for you.
*April 26, 2014*

**physics**

force = pressure * area weight of 10 kg = 9.81*10 = 98.1 N weight of man = maybe 100kg*9.81 = 981 N 981 /50A = pressure force up on other end = pressure * A = 981/50 = 19.62 Newtons well he needs about 100 N and his whole weight only produces about 20 N even though he is a 220...
*April 26, 2014*

**Science**

W*50 + 25*5 + 10*75 = (W+25+10)40 10 W = 525 W = 52.5 gf whatever a gf is :)
*April 26, 2014*

**statistics**

Binomial distribution P = 4420/13168 = .33566 1-p = .66434 P(0) = c(5,0) p^0 (1-p)^5 = 1 * 1 * .66434^5 = .129 P(1) = c(5,1)p^1 (1-p)^4 = 5 *.33566 * .66434^4 = .3269123 P(2) = c(5,2)p^2(1-p)^3 = 10 *.33566^2 * .66434^3 = .330347 sum = .657 P(5) = .66434^5 = .12941
*April 26, 2014*

**Math**

You are welcome :)
*April 26, 2014*

**Math**

ends 2 * 2.5 * 4 = sides 2 * 6 * 4 = bottom 6*2.5 = multiply and add
*April 26, 2014*

**h school**

snow
*April 26, 2014*

**h school**

beaver hides
*April 26, 2014*

**h school**

shale oil ?
*April 26, 2014*

**Math**

-1 -8 +12 | 1 0 +3 24 -36 | 0 1 +1 +8 -12 |-1 0 +3 24 -36 |+0 1 +1 +8 -12 |-1 0 +1 +8 -12 |+0 1/3 HEY, as we should have seen immediately, the second equation is a multiple of the first. THERE IS NO SOLUTION!!! They are the same line on a graph, no intersection. I think it was...
*April 26, 2014*

**physics**

Unfortunately I do not see the drawing.
*April 26, 2014*

**physics**

The sum of the externally applied forces must be zero, and the sum of the externally applied torques must be zero.
*April 26, 2014*

**Calculus Please Help2**

let z = x^6-2 then dz = 6 x^5 dx I think you can take it from there :)
*April 25, 2014*

**physics**

Great !
*April 25, 2014*

**physics**

using your figures g moon = F/m = G M/r^2 = 6.67^10^-11*7.35*10^22 /3.03*10*12 =16.17*10^-1 = 1.67 m/s^2 I guessed 9.8/6 = 1.63 so I would be a little off
*April 25, 2014*

**physics**

Your way I get (1/2)(21/25) vi^2 = G M [1/R - 1/(R+h) ] 21/50 (1210)^2 = 6.67*10^-11 * 7.35*10^22 [ 1/1.74*10^6 - 1/(1.74*10^6+h) ] .615*10^6=49*10^11 (.575*10-6 - z) where z = 1/(1.74*10^6+h) .1255*10^-6 = .575*10^-6 - z z = .449*10^-6 1/z = 2.22*10^6 = 1.74 *10^6 + h h = ....
*April 25, 2014*

**physics**

well, what did you calculate for g moon? If it is not something like 9.81/6 it is wrong, but the 1/6 of earth gravity is a rough approximation.
*April 25, 2014*

**physics**

Oh well, as a first guess since you did not say I will assume g moon = g earth/6 = 9.8/6 = 1.63 m/s^2 so a = -1.6 v = Vi - 1.6 t (2/5)(1210) = 1210 - 1.6 t 1.6 t = 1210 (3/5) t = 454 seconds h = Vi t - ((1/2)(1.6) t^2 = 384,447 meters
*April 25, 2014*

**Algebra**

No problem. You are welcome :)
*April 25, 2014*

**Algebra**

Like I said before when I had to guess what the question was :)
*April 25, 2014*

**Algebra**

if x = 5, the denominator is zero and the function is undefined and x = 5 is excluded from the domain.
*April 25, 2014*

**Physics**

From an ancient reply: fr = fs[(v-vd)/(v-vs)] fs is the frequency of the source, relative to the medium carrying the waves. We assume that is also the speed with respect to the ground (no wind) fr is the received frequency. v is the speed of sound in the air. vd is the speed ...
*April 25, 2014*

**calculus help**

LOL - I do not even remember doing that !
*April 25, 2014*

**calculus help**

vol = pi r^2 h so h = V/(pi r^2) area = pi r^2 + 2 pi r h area = A = pi r^2 + 2 pi r V/(pi r^2) A = pi r^2 + 2 V /r dA/dr = 0 = 2 pi r -2 V /r^2 V / r^2 = pi r V = pi r^3 but V = h (pi r^2) so h (pi r^2) = pi r^3 h = r or h = D/2
*April 25, 2014*

**Algebra**

It is incorrect then The area of a circle is pi r^2 a = pi r^2 r^2 = a/pi r = sqrt (a/pi) = sqrt a/srt pi NOT (sqrt a) / pi NO ! The text did NOT make that error, like no way. It is in your parentheses.
*April 25, 2014*

**Algebra**

by the way you wrote that wrong pi r^2 = A r^2 = (A/pi) r = sqrt (A/pi) which is sqrt A/sqrt pi
*April 25, 2014*

**Algebra**

r = sqrt(50) /sqrt pi = sqrt (25*2) /sqrt pi = (5 sqrt 2) /sqrt pi 3.98 ft
*April 25, 2014*

**calculus help**

mean value theorem backwards ? :) df/dx = 1/(x-3) f(9) = ln(6) = 1.79 f(5) = ln(2) = .69 f(9)-f(5) = 1.0986 divide by 4 = .27465 1/(x-3) = .27465 ln(x-3) = x-3 = 1/.27465 x = 3 + 3.64 x = 6.64 check 1/(6.64-3) = .2747
*April 25, 2014*

**calculus help**

length = 2 W + L area = W*L = 600 so L = 600/W C = 3(2W) + 5 L C = 6 W + 5(600/W) = 6 W +3000/W minimize C dC/dW = 0 = 6 - 3000/W^2 W^2 = 3000/6 = 500 W = 10 sqrt 5 = 22.36 then L = 26.83 is that max or min? d^2 C/d W^2 = 3000/W^4 second derivative is always positive so ...
*April 25, 2014*

**Physics**

1.5 *10^-5 ( 9.4*10^9 /16*10^9) = .881 * 10^-5 = 8.81 *10^-6 m I am surprised that it is stiffer in tension than in compression
*April 25, 2014*

**calculus help**

F = m a the only force is g = -1.6 m so F = - 1.6 m = m a so a = -1.6 m/s^2 v = integral a dt = -1.6 t + constant when t = 0, v = 32 so v = -1.6 t + 32 h = integral v dt h = -(1.6/2) t^2 + 32 t + constant when t = 0 , h = 3 so h = -0.8 t^2 + 32 t + 3 what is max h? answer: ...
*April 25, 2014*

**Geometery help**

LOL, no, but I think you mean (-x, -y)
*April 25, 2014*

**incomplete**

What do you want? Where it is undefined is where 9x = 45 or x = 5
*April 25, 2014*

**math**

what about it? 3750 - 125 w + w^2 ???
*April 25, 2014*

**Math**

in a solid mass closely fitting the shape. (no gaps)
*April 25, 2014*

**Math**

http://www.miniwebtool.com/standard-error-calculator/ 8/sqrt(25) = 8/5 = 1.6
*April 25, 2014*

**Math**

try: http://davidmlane.com/hyperstat/z_table.html
*April 25, 2014*

**Algebra 1 (Reiny)**

If you have not learned about imaginary roots then you have a typo in number 1 You can not solve x^2 = -2 Unless you have had complex numbers. You can do number two the second way I did it, by factoring.
*April 25, 2014*

**Algebra 1 (Reiny)**

1. x^2 = -2 x = +/- i sqrt 2 imaginary roots 2. x = [ 6 +/- sqrt (36+28) ] / 2 = 3 +/- 4 7 or -1 or just factor it (x-7)(x+1) = 0
*April 25, 2014*

**Math**

n^2 - 2 n - 4 = 0 n = [ 2 +/- sqrt(4 + 16) ] / 2 n = [ 2 +/- 2 sqrt 5 ]/2 n = 1 +/- sqrt 5
*April 25, 2014*

**Physics**

As a charged particle passes through a magnetic field it experiences a force perpendicular to its direction of motion. That is a centripetal force leading to centripetal acceleration v^2/r so F = q v B and F = m v^2/r so q v B = m v^2 / r and finally r = m v/(q B)
*April 24, 2014*

**sorry 2*4 = 8**

3 x -4(x+2) = 144 3x - 4 x - 8 = 144 -x = 152 x = - 152
*April 24, 2014*

**Math**

x/4 - (x+2)/3 = 12 multiply by 3*4 or 12 to clear fractions 3 x -4(x+2) = 144 3x - 4 x - 2 = 144 -x = 146 x = - 146 in the second one multiply through by 28 and in the third by 30
*April 24, 2014*

**math(compunded interest )**

1.1^n = 4 n log 1.1 = log 4 n = log 4/log 1.1 = 14.5 (1 + r/2)^10 = 3500/2000 10 log (1 + r/2) = log 1.75 log (1 + r/2) = .0243 1 + r/2 = 1.05756 r/2 = .05756 r = .115 or 11.5 %
*April 24, 2014*

**math(compunded interest )**

1.08^3 = 1.2597 1.25971 * 1000 = 1,259.71
*April 24, 2014*

**Statistics**

You included every single child so your results are exact.
*April 23, 2014*

**calculus help**

dy/dx = 9 integral dx/(1-x^2)^.5 y = 9 sin^-1 x + c note sin pi/6 = sin 30 deg = 1/2 so y(1/2) = 9 (pi/6) + c = 1 so c = 1 - 3 pi/2 so y = 9 sin^-1 x + (2-3 ) pi/2
*April 23, 2014*

**maths**

That is interesting. By the way you can not copy and paste here. I see no data. (and also no question)
*April 23, 2014*

**physics**

f = 1/T omega = 2 pi f A omega = .7 *2 pi f A omega^2 = .7 (2 pi f)^2
*April 23, 2014*

**Physics**

about time you did some. I passed the course in 1954.
*April 22, 2014*

**Physics**

d = .5 a t^2 840 = a(1024) a = .820 m/s^2 v = a t = .820 * 32 = 26.2 m/s
*April 22, 2014*

**algebra**

A=P(1+I)^3 You mean A=P(1+I)^t t just happens to be 3 years here 49130 = 40960 (1+i)^3 1.19946 = (1+i)^3 take cube root 1 + i = 1.0625 or i = 6.25 %
*April 22, 2014*

**Physics waves- help please**

You hear a high pitch as he comes toward you, lower as he leaves So the actual frequency is lower than you hear. In fact you know it is between 195 and 147 Fl = [(v + vl)/(v+vs) ] Fs where Fl = frequency heard Fs = Frequency of source v = v sound vl = v listener vs = v source ...
*April 22, 2014*

**Algebra**

b^2 = + 5/2 b = +/- sqrt (2.5)
*April 22, 2014*

**Physics**

v = vi + a t x = xi + vi t + (1/2) a t^2 for example "Place the man so that he is positioned at the 0.00 metre (m) mark. Set the initial velocity at -2.00 m/s and the acceleration at 0.50 m/s2. In a data table, record the time when the man is momentarily stopped and ...
*April 22, 2014*

**Science**

see saw heavy person on one end light person on the other end. put the pivot at the center of mass so it balances. Ignoring the mass of the plank itself heavy mass (distance to c mass) = light person mass (distance to c mass) in general sum of m1 x1 + m2 x2 +....mi xi = (m1 + ...
*April 22, 2014*

**Math**

hypotenuse^2 = 18^2 + 22*2
*April 21, 2014*

**calc**

(1/2) b h = A (1/2) b (11.5) = 85 b = 14.8 if we need it 2 dA/dt = b dh/dt + h db/dt 2 (3) = 14.8 (1) + 11.5 db/dt - 8.8 = 11.5 db/dt db/dt = - .765
*April 21, 2014*

**Calc**

LOL, math versus physics, round 4596
*April 21, 2014*

**Calc**

dy/dt = dy/dx * dx/dt dy/dx = 4 (1/2) (2x+2)^-.5 (2) = 4(2x+2)^-.5 dx/dt here = 5 so dy/dt = 20 (2x+2)^-.5 = 20/2 = 10 so velocity vector at (1,8) is V =5 i + 10 j the radius vector here is R =1 i + 8 j I want the component of the velocity vector in the direction of the radius...
*April 21, 2014*

**College Algebra**

do you mean n = c e^(at) ? I will assume that. when t = 0 , e^at = e^0 = 1 so c = 148 whet t = 2 333 = 148 e^(2a) 2.25 = e^(2a) so ln 2.25 = 2 a .8109 = 2 a a = .405 so n = 148 e^(.405 t)
*April 21, 2014*

**calculus help**

well, first I factor it to see where zeros of the numerator and denominator are: (2x+3)(x-4) / [ (3x-1)(x-2) ] so you know the thing is going to be undefined at x = 1/3 and at x = 2 Now where are derivatives + , - and 0 ? If you use this you get a graph https://www....
*April 21, 2014*

**physics**

.01 meter/900 = 1.11*10^-5 meters` sin T = T = 664*10^-9/1.11*10^-5 = .0598 .0598 * 2.75 = .164 meters
*April 20, 2014*

**physics**

Y1 = lower right wall tan i = Y1/(L/2) Y1 = (L/2) tan i Y2 = upper right wall = L-Y1 = L - (L/2) tan i or Y2 = L (1 - .5 tan i) now in upper triangle tan i = L(1 - .5 tan i)/.8 L or tan i = 1.25 - .625 tan i 1.625 tan i = 1.25 tan i etc
*April 20, 2014*

**Maths**

F = T + 10 F + 3 = 3(T+3) T + 10 + 3 = 3 T + 9 2 T = 4 T = 2 F = 12
*April 20, 2014*

**Physics waves**

2 I have no idea if the nodes at the end count as two of the three I will assume yes so we have one node in the middle, the second harmonic Adjacent nodes are (1/2) lambda apart so the length of the string is a wavelength
*April 20, 2014*

**Physics waves**

1) 3 Hz, the difference frequency sin a + sin b = 2 sin .5(a+b) cos.5 (a-b) or twice the average frequency times half the difference frequency YOU HEAR TWO maxima per cycle (he square of the amplitude so you hear F1-F2 nor (1/2) (F1-F2)
*April 20, 2014*

**math (cant figure it out)**

Activity Boys Girls Total Walk------ 3--- 6 ---> 9 Bike------ 5--- 3 ---> 8 Skateboard 2 ---1 ---> 3 Total------10---10---> 20 ______________ What percentage of the total students chose skateboarding? 100 (3/20) = 15% so yes, none of these 10% 20% 30% none of these...
*April 20, 2014*

**Physics waves- check answers please**

You are welcome.
*April 20, 2014*

**Physics waves- check answers please**

I agree on all but #3. If by loop they mean antinode they occur 6 times including the ends. The distance from a node to an antinode is 1/4 lambda. I see ten quarter wavelengths in the 24 feet so 10( lambda/4) = 24 lambda = 2.4 *4 = 9.6 meters
*April 20, 2014*

**physics**

Generally yes, when you cook something the temperature goes up, storing heat that can be released later when the fire goes out.
*April 20, 2014*

**Social Studies**

I should have said between Iraq, Turkey, Syria, and Iran.
*April 20, 2014*

**Social Studies**

When the Middle East was split up into "mandates" under European countries after the Ottoman Empire was demolished, little attention was given to the ethnic or historical backgrounds of the various groups of people. Lines were arbitrarily drawn and this was called &...
*April 20, 2014*

**Social Studies**

Once again - C
*April 20, 2014*

**Dynamics**

at top of loop centripetal acceleration = g or it leaves the track g = v^2/a height at top of loop = 2 a potential energy at top of loop = m g h = 2 m g a total energy at top of loop = .5 m v^2 + 2 m g a = .5 m g a + 2 m g a = 2.5 m g a so h = 2.5 a
*April 20, 2014*

**math**

for combinations: n!/[r!(n-r)!] 6! /[ 3! (6-3)! ] 6*5*4/ (3*2*1)
*April 20, 2014*

**SPAM**

Some of these are virtually identical and some are terribly easy. Try them before posting.
*April 20, 2014*

**Chemistry**

OOps sorry, thinking atomic number :(
*April 20, 2014*

**Chemistry**

1.2 * 5 grams/ liter = 6 grams/liter Na = 11 g/mol Cl = 35.5 g/mol Na Cl = 46.5 g/mol 6/46.5 = .129 M
*April 20, 2014*

**statistics**

.4686 http://davidmlane.com/hyperstat/z_table.html
*April 20, 2014*

**physics**

60,000 m/3600 s = 16.7 m/s 80,000 m/3600 s = 22.2 m/s (16.7 - 22.2)m/s / 5 s = -1.11 m/s^2
*April 20, 2014*

**Physics**

I am not sure I have ever seen a really watertight shipping container but anyway:) Volume of container = 6*2.2*2.3 = 30.36 m^3 Buoyancy of container = 30.36*1025 g N = 31,119 g N Buoyancy of lift bag = 1025 g (4/3) pi r^3 = 21,094 g N total up force = 52,213 g N total down ...
*April 19, 2014*

**Physics**

d bus = .5 a t^2 = .25 t^2 d student = d bus + 10 = 3 t so .25 t^2 = 3 t - 10 .25 t^2 -3 t + 10 = 0 t^2 - 12 t + 40 = 0 t = [ 12 +/- sqrt(144 -160) ] /2 oh my, complex t student only catches bus in imagination
*April 19, 2014*

**Physics**

22,000/3600 = 6.11 m/s 85 000/3600 = 23.61 m/s average speed during acceleration = 14.86 m/s t = distance/speed = 200/14.86 = 13.46 s a = speed change/time = 17.5/13.46 = 1.3 m/s^2
*April 19, 2014*

**Calculus Help**

b) the answer is in (a) twice 2178 feet I think you can figure the rest out
*April 19, 2014*

**Calculus Help**

90 mi/hr = 132 ft/s (a) first how long and how far to reach 132 ft/s v = 0 + 4 t 132 = 4 t t = 33 s to reach 132 d = .5 a t^2 = 2 (33)^2 = 2178 ft to reach cruising speed 15*60 = 900 seconds total 900 - 33 = 867 seconds left how far at cruising speed 132 ft/s * 867 s = 114,...
*April 19, 2014*

**calculus help**

Nothing. I use SCI unless ordered otherwise :)
*April 19, 2014*

**calculus help**

4.14 m/s^2 = 13.6 ft/s^2 :)
*April 19, 2014*

**calculus help**

22 mph = 9.83 m/s 50 mph = 22.35 m/s a = change in velocity/time = (22.35 -9.81)/3 = 4.18 m/s^2 or about half g
*April 19, 2014*

**math**

a) y = 1 x - 3 slope = m = 1 slope of perpendicular = -1/m = -1/1 = -1 so y = -x + b 2 = -3 + b b = 5 so y = -x + 5 do the other the same way
*April 19, 2014*

**SkatingDJ**

It must be numbered 0 to 5. Never heard of that before. odd = 1 3 5 even = 0 2 4 prob of odd = 1/2 colors = 2 y + 1 b + 1 g so prob y = 2/4 = 1/2 the two events are independent so p = (1/2)(1/2) = 1/4
*April 19, 2014*

**math**

r^2 = k V k = r^2/V if you multiply r by 9, then V by 81 k = (9r)^2/81V = r^2/V so e
*April 19, 2014*

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