Saturday

February 13, 2016
Total # Posts: 25,219

**Math**

-2x+y=1 -4x+y=-1 ------------ subtract because coefficient of y is the same -2x + 4x + 0 = 1+1 = 2 2 x = 2 x = 1 then -2(1) + y = 1 y = 3 so in the end (1,3)
*December 3, 2015*

**Pre calculus**

You are welcome.
*December 3, 2015*

**Pre calculus**

the slope is: (-6 - -7) / (-8 - -5) = 1/-3 = -1/3 the slope is also (y - -7) / (x - -5) = (y+7)/(x+5) so (y+7) = (x+5)(-1/3)
*December 3, 2015*

**Simple pre cal**

There are two values of y for z = 15 !
*December 3, 2015*

**Physics**

Instead of 90 degrees to the shaft (optimal) You are at 120 which is 30 degrees off. so your force perpendicular to the shaft is F cos 30 The torque is F cos 30 * 0.39 so F cos 30 * 0.390 = 49.0
*December 3, 2015*

**Physics**

http://www.jiskha.com/display.cgi?id=1449174010
*December 3, 2015*

**Mathematics**

new length and width = 19-2x area of base = (19-2x)^2 height = x so V = x (19-2x)^2
*December 3, 2015*

**Social Studies**

Lots of things like languages and foods and religions and boat designs. Did you mean to post a list?
*December 3, 2015*

**Easy math question**

7 x = 2 y + 5 2 y = 7 x - 5 y = (7x-5)/2
*December 3, 2015*

**math**

Speedy d at 110 and d at 130 t = d/110 + d/130 = d(.01678) Cannon 2 d at 120 t = 2 d/120 = d/60 = d(.01667) Speedy's time is bigger, he lost
*December 3, 2015*

**typo**

so c = -20 I do not know why I said that, typo while copying and pasting
*December 3, 2015*

**Algebra 2 (Math)**

a x^2 + b x + c (1) a(4) + b(-2) + c = -20 (2) a(0) + b(0) + c = -4 (3) a(16) + b(4) + c = -20 -------------------------------- eqn (2) tells us that c = -4 so c = -20 (1) a(4) + b(-2) = -16 (2) a(0) + b(0) = 0 (3) a(16) + b(4) = -16 ------------------------------ (1) -8 a + 4...
*December 3, 2015*

**Physics**

This is the same as the one with the skaters, just different numbers momentum before = .255 v + .365 * 0 momentum after = .255 (-.118) + .365*.649 momentum after = momentum before, solve for v
*December 3, 2015*

**Pre calculus**

That is a straight line with slope -2, it has perfectly finite values for any real x so B
*December 3, 2015*

**algebra**

for example: http://ncalculators.com/statistics/linear-regression-calculator.htm
*December 3, 2015*

**algebra**

google linear regression to get software calculator to fit straight line to your data.
*December 3, 2015*

**Physics**

momentum is zero before so zero after. 61*.63 + m* -.86 = 0 note speeds are opposite so velocity of one or the other is negative m = 61 (.63/.86)
*December 3, 2015*

**Math**

12 * 3 / 4 = 3*3 = 9
*December 3, 2015*

**Maths**

2 w + 2 (w+5) = 26 2 w + 5 = 13 2 w = 8 w = 4 w+5 = 9
*December 3, 2015*

**Please Check My Work: College Physics**

N is normal force from road m g = N cos T so N = m g/cos T N has inward component = N sin T so inward component of force = m g sin T/cosT = m g tan T Ac = m v^2/R m g tan T = m v^2/R tan T = v^2/( Rg) as you know tan T = 400/(200*9.81) tan T = .204 T = 11.5 degrees
*December 3, 2015*

**Please Check: College Physics**

You are welcome.
*December 3, 2015*

**Huh ? horizontal, no g , friction force - 12**

F = m a -12 = 8 a a = -1.5 m/s^2 yes 0 = 6^2 + 2 a x 0 = 36 -3 x x = 12 m
*December 3, 2015*

**sms**

1.44/16
*December 3, 2015*

**History**

I would also choose A although he did want to get home.
*December 3, 2015*

**math/technology**

If there are two there are two.
*December 3, 2015*

**physics**

2 kg * 9.81 = 19.62 N weight loses (19.62-12.34) = 7.28 N in water 7.28 N /9.81 = .7421 Kg of water displace .7421 kg * 1 m^3/1000 kg = 7.421 * 10^-4 m^3 = volume of mass mass of light fluid displaced = 7.421 *10^-4 m^3 * .78 * 10^3 = .579 kg weight of light fluid displaced...
*December 3, 2015*

**calculus**

MITx question ?
*December 2, 2015*

**prealgebra**

w and w+3 perimeter = 2 w + 2 (w +3) = 58 4 w + 6 = 58 4 w = 52 w = 13 so 13 by 16
*December 2, 2015*

**Precalculus**

2(1-sin^2 T) + sin T = 1 2 - 2 sin^2 T +sin T - 1 = 0 -2 sin^2 T + sin T +1 = 0 2 sin^2 T - sin T - 1 = 0 let z = sin T 2 z^2 - z - 1 = 0 (2 z +1)(z-1) = 0 z = -1/2 or z = 1 so sin T = -1/2 gives T = 150 deg or -30 deg sin T = 1 at 90 deg
*December 2, 2015*

**Calc 3**

Do you know about divergence and curl ? I have a sneaking suspicion that the divergence and curl (no sources or sinks and no vortices with singularities at the origin) are zero and the flux and line integral around the closed surface are zero.
*December 2, 2015*

**math**

12 by 8 by 5 five is the height because in vertical plane. 12 by 8 is the top and bottom. Sketch a drawing of it !
*December 2, 2015*

**chem.**

Fe = 56 g/mol 3 O = 3*16 = 48 g/mol so a mol of Fe2O3 is 160 grams and a mol of Fe is 56 grams 3 g Fe = 3/56 mol Fe that will give me half as many mols of Fe2O3 so 3/112 mols Fe2O3 (3/112) * 160 = 4.29 grams of Fe2O3 ========================
*December 2, 2015*

**Physics**

force = change on momentum/change in time = .045 * 59 / .001 = 2655 Newtons
*December 2, 2015*

**MATH SUPER URGENT!**

50 * 20 = 1000 strip width = s interior dimensions (50-2s)(20-2s) = half original = 500 1000 - 140 s + 4 s^2 = 500 so 4 s^2 - 140 s +500 = 0 s^2 - 35 s + 125 = 0 s = [35 +/- sqrt (1225-500) ]/2 s = [35+/- 26.92 ] /2 s = 30.96 or 4.04 must be 4.04 because strips of 31 each end...
*December 2, 2015*

**Algebra**

d = 100 - q 25 q + 10 d = 2140 25 q + 1000 -10 q = 2140 15 q = 1140 q = 76 so d = 24
*December 2, 2015*

**Social studies**

nope, which is not an advance in technology but simply something you do.
*December 2, 2015*

**algebra**

Huh, what you typed is not true.
*December 2, 2015*

**Algebra**

2x -5x -11 >/= 4x + 17 -3x >/= 4x + 17 0 >/= 7x + 17 7x </= -17 x </= -17/7
*December 2, 2015*

**Pre Calc**

http://www.jiskha.com/display.cgi?id=1449008243
*December 2, 2015*

**Pre Calc**

I think I did this yesterday 5, 12, 13 triangle cos^2 - sin^2
*December 2, 2015*

**MATH**

8 log5(x) + 4 log5(y)
*December 2, 2015*

**MATH**

log5 (x^2y)^4 4 log5(x^2y) 4 [ log5 (x^2)+ log ( y) ] 4 [ 2 log5 (x)+ log ( y) ]
*December 2, 2015*

**science**

By the way I did all this as if a kg was a force If you need Newtons and Newton meters, multiply final answers by 9.81
*December 2, 2015*

**science**

get end forces up first beam kg = 6*1500 = 9000 kg at center forces F1 up at left and F2 up at right moments about left to get F2 F2*6 = 1000*1.5 + 11000*3 + 3000*4.5 so F2 = 48,000/6 = 8,000 up at right end total mass = (1+11+3)10^3 = 15,000 kg so F1 = 15,000- 8000 = 7,000 up...
*December 2, 2015*

**math**

2w+2L any old whole numbers for L and w
*December 2, 2015*

**algebra please explain**

-3
*December 2, 2015*

**math**

125,000 - 125,000 = 0
*December 2, 2015*

**Mathematics**

mean = 165 defective if <156.2 variance = 16 so sigma = sqrt 16 = 4 (did you notice that?) then use Davidlane http://davidmlane.com/hyperstat/z_table.html I get 0.0139 or 1.39 percent
*December 2, 2015*

**Mathematics**

mean = 165 defective if <156.2 variance = 16 so sigma = sqrt 16 = 4 (did you notice that?) then use Davidlane
*December 2, 2015*

**Social Studies**

true, Nederlands
*December 2, 2015*

**Social Studies**

yes
*December 2, 2015*

**Social Studies**

as I remember you are right :)
*December 2, 2015*

**Science**

how wide has nothing to do with this Upstream speed = 8.9 sin T - 2.4 if we do not want to go upstream, that must be zero so 8.9 sin T = 2.4 T = 15.6 degrees
*December 2, 2015*

**Social Studies**

yes, Catholic
*December 2, 2015*

**Social Studies**

Yes, center is Andes and Jungle :)
*December 2, 2015*

**Social Studies**

No idea, assume you know
*December 2, 2015*

**Social Studies**

yes, that is what missionaries do.
*December 2, 2015*

**Math**

Amy if there are F friends, then each gets 40/F say you had 4 people and 40 grapes each would get n = 40/4 = 10 grapes
*December 2, 2015*

**Math**

n = 40/f
*December 2, 2015*

**Physics**

20 * x = 10 (1.08 -x) 20 x + 10 x = 10.8 30 x = 10.8 x = .36 so .36*10^-10 = 3.6 * 10^-11 meters
*December 2, 2015*

**History**

There were no term limits for presidents when I started voting. That was after George Washington rode off into the sunset. He did start a tradition of term limits, but there was no law and in fact FDR served more than two before and during WW2.
*December 2, 2015*

**Algebra 2**

log3 (x) = 9 well what I would do is 3^(log3(x)) = x = 3^9 same for #2 3) e^lnx = x = e^2 Just one more step from what you showed
*December 2, 2015*

**math**

6.3
*December 2, 2015*

**Math - are you sure?**

Do you really mean? x+2y+z=1 -x+y+0z=4 4x-0y+3z=-1
*December 2, 2015*

**Physics**

Hi = 1.6 u = 6.4 cos 65 forever = x coordinate Vi = 6.4 sin 65 initial Vertical problem: v = Vi - 9.81 t h = Hi + Vi t - 4.9 t^2 so 0 = 1.6 + 5.8 t - 4.9 t^2 or 4.9 t^2 - 5.8 t - 1.6 = 0 t = [ 5.8 +/- sqrt (33.64 + 31.36)]/9.8 t = (5.8 +/- 8.06)/9.8 we want + answer t = 1.41 ...
*December 2, 2015*

**Maths**

x^2 = 2 y x = +/- sqrt (2y)
*December 2, 2015*

**7th Math**

Er 1.7 *10^22 P 1.3*10^22 Ha 4*10^21 Ma 3*10^21 Ce 9 * 10^20
*December 2, 2015*

**7th Math**

You are welcome.
*December 2, 2015*

**7th Math**

1. right 2. right , right
*December 2, 2015*

**English**

yuuk, insensitive Easy for you to say :)
*December 2, 2015*

**English**

radiant star looks like a symbol AND a metaphor to me Oh come on - B
*December 2, 2015*

**English**

Note " ... device used to adjust ...." so I think C I also think the metaphor stinks.
*December 2, 2015*

**English**

Unfortunately I have to agree with Sid,V note: " ... there comes a time ... "
*December 2, 2015*

**Maths**

2 w + 6 t w = 11 w (2 + 6 t) = 11 w = 11 / (2 + 6 t)
*December 2, 2015*

**ntc**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*December 2, 2015*

**Oxford, maths**

x + y = 10 y = -x + 10 if x = 0 , y = 10 if y = 0 , x = 10 draw line through those two intercept points
*December 2, 2015*

**math**

2/3 (12) = 8 4.5 * 12 = 54 54 + 8 = 62
*December 2, 2015*

**Pre-Cal**

sin 42 = h/400
*December 1, 2015*

**math**

cross section area = pi(.9)^2 - pi(.7)^2 volume = 2.5 * pi (.81-.49)
*December 1, 2015*

**Algebra**

slope = (72-18)/8-2) = 54/6 = 9 9 = (y-18)/(x-2) so y-18 = 9(x-2)
*December 1, 2015*

**Math**

w/L = 2/5 4/10 = 2/5
*December 1, 2015*

**Math**

v = rowing speed u = current speed 2 miles = (v+u)(20/60) 2 miles = (v-u) (1) ============================ then 2 = v/3 + u/3 2/3 = v/3 - u/3 ------------------ 4/3 = 2 u/3 u = 2 etc
*December 1, 2015*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*December 1, 2015*

**Geometry**

b can NOT be 45 degrees and the magnitude MUST be bigger than 24.1 north = 10 + 20 cos 45 = 24.1 agree east = 20 sin 45 = 14.1 agree mag = sqrt (24.1^2+14.1^2) = 27.94 tan deg e of n = 14.1/24.1 so deg e of n = 30.3 degrees East of North
*December 1, 2015*

**Algebra 2**

a = k/b 2 = k/15 k = 30 a = 30/6 a = 5
*December 1, 2015*

**Pre Calc**

(x-2)(x-2) (-2x-1)(x+1) = 0 roots 2 2 -1/2 -1
*December 1, 2015*

**Algebra**

w(w+2) = 224 w^2 + 2 w - 224 = 0 (w-14)(w+16) =0 w = 14
*December 1, 2015*

**Algebra**

2 L + 2 w = 58 so L + w = 29 and L=29-w w (29-w) = 204 29 w - w^2 = 204 w^2 - 29 w + 204 = 0 w = [ 29 +/- sqrt(841-816) ] / 2 w = [ 29 +/- 5 ]/2 w = 34/2 = 17 L = 12 that works or L =17 and w = 12
*December 1, 2015*

**MATH**

0.40 x = 56 x = 56/.4 = 560/4
*December 1, 2015*

**please check typing**

What you wrote makes no sense to me beginning with is it a quadrilateral (4 sides) or a triangle (3 sides)
*December 1, 2015*

**Snap - 3rd grade technique**

Many third grades do division the way you and I learned, but more and more are using other methods that link into common core. I am not sure what methodology this student might be learning.
*December 1, 2015*

**3rd grade math**

well, divide by two to get what she drives each day 752/2 = ? I am not sure how your class does division 7/2 = 3 remainder 1 thus 5 becomes 15 regrouping 15/2 = 7 remainder 1 thus 2 becomes 12 regrouping 12/2 = 6 NO remainder :) so I get 376 b) if she can do the whole trip in ...
*December 1, 2015*

**physics sound waves**

lam = wavelength second lowest with open ends: lam = Lo second lowest with closed end lam = 4/3 Lc f proportional to 1/Lam so f open = k/Lo and f closed = 3k/4Lc difference frequency = k (1/Lo -3/4Lc) third lowest open Lam = (2/3) Lo third lowest closed Lam = (4/5) Lc f open...
*December 1, 2015*

**science help**

NO ! similar charges repel
*December 1, 2015*

**science help**

LOL, like charges repel
*December 1, 2015*

**science check please**

Hey, hang on ! THINK!!! The gravitational field of earth pulls the air molecules toward the center of earth, just like it pulls water molecules in the ocean toward the center. As a result, as you go toward the center of earth, either in air or in water, you get more and more ...
*December 1, 2015*

**Pre Calc**

cos x + sin x LOL, I just looked at it and wrote it because sin x/tan x = sin x /(sin x/cos x) = cos x etc
*December 1, 2015*

**Pre Calc**

2 z^2 - 3 z + 1 = 0 (2z-1)(z-1) = 0 z = 1/2 or z = 1 so when is sin x = 1/2 ? and when is sin x = 1 ?
*December 1, 2015*

**Precalculus**

2) log(base7)5=7-6x 5 = 7^(7-6x) = 7^z log 5 = z log 7 z = .827 7 - 6 x = .827 6 x = 6.1729 x = 1.0288
*December 1, 2015*

**Precalculus**

4) 4^(x-5)=8^(x+2) (2^2)^(x-5) = (2^3)^(x+2) 2^(2x-10) = 2^(3x+6) 2x-10 = 3x+6 x = -16 agree
*December 1, 2015*