Wednesday

July 23, 2014

July 23, 2014

Total # Posts: 17,491

**math**

first pie cost 6 * 20 = 120 cents second pie cost 8 * 30 = 240 cents it doubled which is an increase of 100 % [ (240 -120)/120 ] * 100 = 100%

**Algebra 1**

This is Algebra 1 where ?

**Algebra 1**

1 agree https://hrdag.org/convenience-samples-what-they-are/ 2 agree http://en.wikipedia.org/wiki/Sampling_%28statistics%29#Systematic_sampling

**Maths**

You need five if you have no typos. Draw it on a piece of paper. to use math: tile area = 1/6*1/6 = 1/36 rectangle area = 1/6 * 5/6 = 5/36 5/36 / 1/36 = 5

**Maths**

Unless you have a typo (which I suspect), five of them in a row would cover it.

**Math**

I am taking the easy way out: http://www.cs.virginia.edu/~lat7h/blog/posts/219.html

**Algebra 1**

If that is Algebra 1, you are at a good school :)

**Algebra 1**

1 Yes (I had to think for a minute:) 2 Yes 3 Yes

**algebra**

2+3 = 5 so 2/5 and 3/5 2/5 = 10/25 3/5 = 15/25 check: 10 + 15 = 25 yes 10/15 = 2/3 check :)

**Disappearing questions now ?????**

There was another question in here that seems to have disappeared but my answer remained ?

**physics**

Heat out of steam= 20 {2260+4.2(100-T)} Heat into water = 80 (T-20) so 4(T-20) = 2260 + 4.2(100-T) 4 T - 80 = 2260 + 4200 - 4.2 T 8.2 T = 6540 T = 797 which is silly of course What it means is that 80 grams of water at 20 degrees simply can not condense 20 grams of steam. The ...

**physics**

Yes, it is just the ratio of heat of vaporization to heat of fusion. I get 2260 J/gram / 334 J/gram = 6.77 g

**Linear algebra**

note first that if a = 1, the first and third rows are identical (infinite number of solutions) then calculate the determinant of the coefficient matrix. Find its zeros. One will be a = 0 Look at second equation when a = 0, x+y = 0 and first equation gives x+y = 0 and third eq...

**math**

9 x^2 - 2 x - 4 = 0 x= [ 2 +/- sqrt (4 + 144 ) ] / 18 x = [ 2 +/- 12.2 ] /18 it says approximate so I will say 12.2 = 12 x = 14/18 or -10/18 or x = .8 or -.6

**physics**

Hey look, Bob Pursley told you how to do these heat gained/ heat lost problems. You keep posting basically the same problem over and over. You are supposed to learn how to do them. Try. Post your attempts.

**Physics**

south momentum = 1900 * 13.6 = 25840 east momentum = 3854 * 9.8 = 37769 same after of course mass = 1900+3854 = 5754 south momentum = 5754 Vs = 25840 Vs = 4.49 m/s east momentum = 5754 Ve = 37769 Ve = 6.56 m/s V = sqrt (Vs^2+Ve^2) = 7.95 m/s tan angle E of S = Ve/Vs = 6.56/4.4...

**Precalculus**

To be in A intersect B, a number must be both prime and a factor of 36 factors of 36 less than 16: 1 3 4 6 9 12 of those only 1 and 3 are prime unite those with the multiples of 4 which are 4 8 12 and you get 1 3 4 8 12

**English help**

Are people who are willing to die for their religion also willing to kill for their religion? In fact is there a relationship between being willing to die for something and being willing to kill for it?

**Math**

I posted two answers below the two you got. n^2 - 9 n + 81/4 = (n-9/2)^2 would be a perfect square n^2 - 6 n + 9 = (n-3)^2 would be a perfect square You can not factor n^2 - 9 n + 9

**Physics**

B) 45 revs/ min * 2 pi radians/rev * 1 min/60 s) = omega final = 4.71 rad/s A) omega = alpha t 4.71 = alpha (85) alpha = ang acceleration = .0554 radians/s^2 so omega = .0554 t

**MATH**

a^2-b^2 = (a-b)(a+b) y^2 - 25(x-1) unfortunately (x-1) is not a square of anything but (x-1)^.5 :) I suppose you could say [ y - 5 sqrt(x-1) ] [y + 5 sqrt(x-1) ] but that is really stretching it

**Math**

Now we could try completing the square n^2 - 9 n + 9 = y n^2 - 9 n = y -9 n^2 - 9 n + (9/2)^2 = y - 9 + 81/4 so n^2 - 9 n + 81/4 is a perfect square :) (n-9/2)(n-9/2)

**Math**

(n-3)(n-3) = n^2 -6 n + 9 unfortunately that 6 is not a 9

**Math**

You are welcome :)

**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

**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

**Trig**

You are welcome.

**Trig**

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

**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 a...

**Science**

sometimes twin stars hold each other in orbit. Imagine the huge gravitational force !

**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 mot...

**Science**

Oh ok I will check

**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.

**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...

**Science**

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

**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

**Math**

You are welcome :)

**Math**

ends 2 * 2.5 * 4 = sides 2 * 6 * 4 = bottom 6*2.5 = multiply and add

**h school**

snow

**h school**

beaver hides

**h school**

shale oil ?

**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...

**physics**

Unfortunately I do not see the drawing.

**physics**

The sum of the externally applied forces must be zero, and the sum of the externally applied torques must be zero.

**Calculus Please Help2**

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

**physics**

Great !

**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

**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 = .48...

**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.

**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

**Algebra**

No problem. You are welcome :)

**Algebra**

Like I said before when I had to guess what the question was :)

**Algebra**

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

**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 o...

**calculus help**

LOL - I do not even remember doing that !

**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

**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.

**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

**Algebra**

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

**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

**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 curvin...

**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

**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: whe...

**Geometery help**

LOL, no, but I think you mean (-x, -y)

**incomplete**

What do you want? Where it is undefined is where 9x = 45 or x = 5

**math**

what about it? 3750 - 125 w + w^2 ???

**Math**

in a solid mass closely fitting the shape. (no gaps)

**Math**

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

**Math**

try: http://davidmlane.com/hyperstat/z_table.html

**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.

**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

**Math**

n^2 - 2 n - 4 = 0 n = [ 2 +/- sqrt(4 + 16) ] / 2 n = [ 2 +/- 2 sqrt 5 ]/2 n = 1 +/- sqrt 5

**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)

**sorry 2*4 = 8**

3 x -4(x+2) = 144 3x - 4 x - 8 = 144 -x = 152 x = - 152

**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

**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 %

**math(compunded interest )**

1.08^3 = 1.2597 1.25971 * 1000 = 1,259.71

**Statistics**

You included every single child so your results are exact.

**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

**maths**

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

**physics**

f = 1/T omega = 2 pi f A omega = .7 *2 pi f A omega^2 = .7 (2 pi f)^2

**Physics**

about time you did some. I passed the course in 1954.

**Physics**

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

**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 %

**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 ...

**Algebra**

b^2 = + 5/2 b = +/- sqrt (2.5)

**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 rever...

**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 + ...

**Math**

hypotenuse^2 = 18^2 + 22*2

**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

**Calc**

LOL, math versus physics, round 4596

**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...

**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)

**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.wolframalph...

**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

**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

**Maths**

F = T + 10 F + 3 = 3(T+3) T + 10 + 3 = 3 T + 9 2 T = 4 T = 2 F = 12

**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

**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)

**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...

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