Wednesday

May 4, 2016
Total # Posts: 26,163

**algebra**

the first way is brute force finding where two lines hit The second way is called "elimination". The third way is called "substitution". They are all ways o find the intersection of those lines.
*April 14, 2016*

**algebra**

or substitute x = 1 - 3y use that in the second one -3(1-3y) -3y=15 -3 + 9 y -3 y = 15 6 y = 18 y = +3 again
*April 14, 2016*

**algebra**

there are lots of other ways, like add the two equations +1 x + 3 y = 1 -3 x - 3 y = 15 ---------------- add -2 x = 16 x = -8 then go back and get y
*April 14, 2016*

**algebra**

first equation is the line y = -(1/3) x + 1/3 second equation (-x-y=5) is the line y = - x - 5 so -x-5 = -(1/3)x + 1/3 2/3 x = -16/3 x = -8 then y = 3 ------------------- check -8+9 = ? 1 yes +24 - 9 = ? 15 yes
*April 14, 2016*

**calculus**

two similar triangles First the stationary situation x/5.5 = (x+14)/16.5 5.5(x+14) = 16.5 x 11 x = 77 x = 7 now start moving x = length of shadow y = woman to pole (x+y)/16.5 = x/5.5 16.5 x = 5.5 x + 5.5 y 11 x = 5.5 y 2 x = y so 2 dx/dt = dy /dt if dy/dt = -6 then dx/dt = -3 ...
*April 14, 2016*

**rs aggarwal math class 8 chapter 8 soluation**

n / (2n -2) (n + 3)/(2n+1) = 2/3 3(n+3) = 2 (2n+1) 3 n + 9 = 4n + 2 n = 7 so n/(2n-2) = 7/12
*April 13, 2016*

**Precalculus**

p = Pi e^kt 2 = e^10 k ln 2 = 10 k .693 = 10 k k = .0693
*April 13, 2016*

**I am not sure**

(x+y)(y+z)=5(x+y)(y+z) one cow = 5 cows Please check for typos
*April 13, 2016*

**Algebra**

>>>>>>> y - 4 --------------------- (y+3) | y^2 - y + 4 >>>>>>> y^2 +3y -------------------- >>>>>>>>>>>> -4y + 4 >>>>>>>>>>>> -4y -12 -------------------- >>...
*April 13, 2016*

**science**

m g h = 700 * 9.81 * 30 Joules Unless you find some way to store that energy and use it to move the elevator back up.
*April 13, 2016*

**geography**

Seeing as how these folks pioneered seafaring in the Indian Ocean I would consider that an important part of their economic activities : http://www.cambridge.org/us/academic/subjects/archaeology/archaeology-asia-sub-saharan-africa-and-pacific/archaeology-seafaring-ancient-...
*April 13, 2016*

**Math**

10/24 = 5/12 so this is a 5, 12, 13 right triangle 39/13 = 3 (of course 26/12 is 3 also) so 5*3 = 15
*April 13, 2016*

**statistic**

http://davidmlane.com/hyperstat/z_table.html
*April 13, 2016*

**Geometry**

120/360 = 1/3 so (1/3) pi r^2 or (1/3)(3.14)(40)(40)
*April 13, 2016*

**algebra**

.08 (25,300) .92 (25,300)
*April 13, 2016*

**math**

2058 = 14 * w * 3 w w^2 = 49 w = 7 L = 21
*April 13, 2016*

**science help pls pls**

http://lcogt.net/spacebook/parallax-and-distance-measurement/
*April 13, 2016*

**math**

1/3 +1/4 = 4/12 + 3/12 = 7/12 so 5/12 = 10 are blue blue = 24 , got it ?
*April 13, 2016*

**Math**

2 n + 5 = 5 n-16 or = 16-5n 21 = 3 n or 7 n = 11 n = 7 or n = 11/7 ====================== check if n = 7 14 + 5 = ??? 35 - 16 19 = 19 check yes if n = 11/7 22/7 + 5 = ???? 16 - 11/7 22/7+35/7 = ??? 112/7 - 55/7 57/7 = 57/7 yes, check
*April 13, 2016*

**Calculus**

h is height x is distance from wall sin T = h/13 cos T = x/13 d cos T /dt = - sin T dT/dt =(1/13)dx/dt or dT/dt = -(1/(13 sin T))(dx/dt) sin t = h/13 at x = 5 h = sqrt (169 - 25) = 12 so sin T = 12/13 so dT/dt = -(1/12)dx/dt = -1/12 radians/second
*April 13, 2016*

**Science**

P1/T1 = P2/T2 140 + 273 = T1 216 + 273 = T2 P1 = (T1/T2)22.3
*April 13, 2016*

**AP Physics**

Area L = volume so if 3 times longer, then 1/3 the area 3 * 21 = 63 ohms
*April 12, 2016*

**AP Physics**

Power = V^2/R = 5434 Watts = 5.434 kw hours = 31*9 = 279 hours so 5.434 kw * 279 hr *.15/(kw hr) = $ 227.41
*April 12, 2016*

**Maths (Proof)**

If you can squish it, it is no longer regular. The sides may be the same but not the angles. Think about a square with hinges at the corners if you squish it into a parallelogram, it still has 4 equal sides but is no longer a regular polygon.
*April 12, 2016*

**Maths (Proof)**

sqrt (2^2 + 5^2) = sqrt 29 agreed the distance from -5,5 to 5,5 is 10 the distance from 0,-7 to 7,0 is 7 Oh my :( not really regular I guess you will have to make a model with 8 equal sides and see if you can sqwish it :) I think you can.
*April 12, 2016*

**Physics**

T = k sqrt L/g sqrt(1.03/9.82) = sqrt (L/9.77) so L = 9.77 (1.03/9.82)
*April 12, 2016*

**Math**

if 40 hours is normal week length 40 x + 7(1.5 x) = 375.78
*April 12, 2016*

**Science**

a= -16 m/s / t = acceleration but what is t? average speed during stop = 24/2 = 12 m/s so time = 80/12 = 20/3 seconds to stop so a = -16(3/20) =-12/5 = -2.4 m/s^2
*April 12, 2016*

**Maths**

B 3 (sin x/ cos x) = cos x 3 sin x = cos^2 x 3 sin x = (1 - sin^2 x) sin^2 x + sin x -1 = 0 let z = sin x z^2 + z - 1 = 0 z = [ -1 +/- sqrt (1+4) ]/2 z = [-1 +/- 2.24 ]/2 z = sin x = .618 or something too big to be a sin of anything
*April 12, 2016*

**Maths**

A x = 0 is a solution also sin x = 2 cos x is tan x = 2 that happens at x = 63.4 degrees and at x = 243.4 degrees convert those to radians by multiplying by pi/180
*April 12, 2016*

**U.S history**

C was much later than the Declaration, in individual states then as Amendments 1 - 10 of US Constitution after Rev War. So C I am not at all sure I agree with you on the second one, think exactly the opposite note the word ANTI- Federalist http://www.google.com/url?sa=t&rct=j&...
*April 11, 2016*

**Geometry**

pi Ro^2 L - pi Rin^2 L = pi L (Ro^2-Rin^2) = pi * 400 (.025^2 - .02^2)
*April 11, 2016*

**Proof read what you typed!!**

to use conservation of momentum you must know all masses and speeds This ::::: " cavity and then suddenly contracting the cavity, forcing the water to shoot out of an opening. A 6.50 daN squid (including the water in the cavity) that is at rest suddenly sees a dangerous ...
*April 11, 2016*

**Science Help**

I think I would pick D because you draw contour lines of constant elevation from point to point. The point is determined by your lat and long. If you do not know where you are, the elevation does not help much.
*April 11, 2016*

**physics**

mass balloon = .0027 kg buoyancy net up force = g [ 4 (1.29-.179) -.0027 ] = g (4.44) = 43.6 N using g = 9.81 m/s^2 F = k x 43.6 = 95 x x = .459 N
*April 11, 2016*

**iron density?**

need density of iron top scale has 2.33 - Viron*916 but Viron = 2.33/density of iron
*April 11, 2016*

**math!!! help**

if two roots are identical then (b-4)^2 - 4(2)(-4)(b+2) = 0 b^2 - 8 b + 16 = -32b - 64 b^2 + 24 b + 80 = 0 (b+4)(b+20) = 0
*April 11, 2016*

**additional mathematic**

Well, first draw a picture now from A or C go right 3 so x = 3 from B go down 4 or from A go up one so y = 3 so D(3,3)
*April 11, 2016*

**Health**

I told you that !!! B is through lungs, not skin The answer is D.
*April 11, 2016*

**Health**

That was not Ms Sue - no way. Respiration occurs through the lungs, not the skin. Perspiration occurs through the skin. That is why it sometimes is a bit smelly I suppose although I am sure it reacts with whatever contamination is already on our skin.
*April 11, 2016*

**Algebra**

[ 1 +/- 19]/10 use w = 2 then L = 9
*April 11, 2016*

**Algebra**

L = 5 w - 1 A = L w = (5w-1)w A = 5 w^2 - w = 18 of whatever sl is 5 w - 1 w - 18 = 0 w = [ 1 +/- sqrt(1+360) ]/10 = [
*April 11, 2016*

**Math: Trigonometry**

cos^2 (2x-pi) = .75 cos (2x-pi) = +/-.866 let z = 2x-pi if z = 30 degrees (pi/3) yes if z = 150 degrees (2pi/3) yes if z = -30 degrees(-pi/3) yes if z = -150 degrees(-2pi/3) if z = -pi/3 then 2 x-pi =-pi/3 2 x = 2 pi/3 x = pi/3 , well that is + if z = +pi/3 2 x = pi + pi/3 = 4...
*April 10, 2016*

**Mathematics**

1 yes horizontal means both y vaues the same. -3 is not -8 vertical means both x values the same. 6 is not 0
*April 10, 2016*

**Physics**

I guess it is at constant velocity m g = 3.1*9.81 = 30.4 N weight mu m g = 43.5 N mu = 43.5/30.4 = 1.43
*April 10, 2016*

**PHYSICS!!**

original a momentum = 80*2.5 original b momentum = -68*1.2 total momentum before and after = 80*.5 - 68*1.2 after = 80*1 + 68 Vb which is final momentum a = 80 final momentum b = total - 80 F on a = (final momentum a - initial momentum a) /0.1
*April 10, 2016*

**Interest**

12,000 (1.056)^n
*April 10, 2016*

**Math**

You are welcome.
*April 10, 2016*

**Math**

(1/-9) /9 = -1/81
*April 10, 2016*

**Science**

http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html
*April 10, 2016*

**Science**

refraction occurs at a boundary where the speed of the wave changes. Google Snell's law
*April 10, 2016*

**stats**

cost = 500 + 200 + 200 = 900 revenue = 250 * 4 = 1000 obviously you can not raise 200 there are 1 + 2 + 4 = 7 winning tickets out of the 250 chance of winning 500 = 1/250 chance of winning 100 = 1/125 chance of winning 50 = 1/62.5 chance of winning anything at all = 7/250 ...
*April 10, 2016*

**Physics CENTER OF MASS**

http://www.jiskha.com/display.cgi?id=1460315436
*April 10, 2016*

**I did this already**

scroll down
*April 10, 2016*

**HELP PHYSICS!! WORK**

m g 8.3 sin 16 + friction force * 8.3 friction force = .6 (m g cos 16)
*April 10, 2016*

**Math ratio**

w/p = 3 or w in quarts = 3 * p in spoons 1 quart = 3* p in spoons for 1 qt so for 1 qt, p = 1/3 spoon for p = 1 spoon you get 3 quarts of water
*April 10, 2016*

**Calculus**

r^2 h = 21.66/pi = 6.89 now you still have to do the problem cost = cost of top and bottom + cost of side x is cost of side metal per in^2 C = 2x pi r^2 + x (2 pi r h) call c = C/2pix what we minimize c = r^2 + r h but we already know h = 6.89/r^2 c = r^2 + 6.89/r luckily you ...
*April 10, 2016*

**Multiplicative inverse**

if you go 10 miles per hour then that is indeed 1/10 hour per mile In general yes do not divide by zero though :)
*April 10, 2016*

**Math Grade 7**

1.5 = 3 times 1/2 3*8.5 = 25.5 minutes which luckily is less than 30 minutes
*April 10, 2016*

**Math**

4 - 3.981 = .019 but 4.001-4 = .001 so no, you are wrong
*April 10, 2016*

**Work**

no, if you push something to get it going you do positive work on it. Your force is in the direction of motion. I you were pushing a spring, it would do negative work on you. -(1/2)k x^2 :) but you would do positive work on it.
*April 10, 2016*

**Block Colliding with a Spring**

I will do more than you asked because I am sure there are more parts weight = m g = 1.6*9.81 = 15.7 N friction force = .48*15.7 = 7.53 N work done by friction = 7.53*.125 = .942 Joules work done by spring = (1/2)(480)(.125^2) = 3.75 J (ANSWER YOU ASKED FOR) total work done by ...
*April 10, 2016*

**Energy of satellite PHYSICS**

That is in Joules if you use m in kg G = 6.67*10^-11 N m^2/kg^2 Me = 5.98 * 10^24 kg Re = 6.38 * 10^6 meters
*April 10, 2016*

**Energy of satellite PHYSICS**

F = G m Me/(h+Re)^2 so let R = 2.3*10^7 + RE centripetal a = v^2/R so F = m a = m v^2/R = mG Me/R^2 or m v^2 = m G Me/R and .5 mv^2 = .5 m G Me/R
*April 10, 2016*

**Geometry**

Now do you know way the biggest rectangle area for 300 foot fence is a square? fence = 2 L + 2 w = 300 so L = 150 - w A = L W A = (150-w)w = 150 w - w^2 so w^2 -150 w = - A w^2 - 150 w + 75^2 = -A + 5625 vertex at w = 75 area = 5625
*April 10, 2016*

**Geometry**

fence length = 300 feet max is a square 300 = 4s s= 300/4 = 75 area = s^2 = 5625
*April 10, 2016*

**Geometry**

total area = (25+8)(12+8) water surface area = 25*12 = 300ft^2 subtract
*April 10, 2016*

**PHYSICS CENTER OF MASS**

.065 is the area of the plater with the hole removed
*April 10, 2016*

**PHYSICS CENTER OF MASS**

mass = 2.79(.23*.37-pi(.08)^2) = 2.79(.0851-.0201) = 2.79 * .065 = .181 kg agree moment in x (forget the 2.79 density) .065 x = .0851*.37/2 - .0201*.125 .065 x = .0157 - .0025 = .0125 x = .192 meter = 19.2 cm now do y of cm the same way
*April 10, 2016*

**Question**

New York is a State New York is a City New York is part of the Northeast region of the US
*April 10, 2016*

**Physics projectile**

constant = kinetic E + potential E = (1/2) m v^2 + m g h but v = Vi - g t so v^2 = Vi^2 - 2 Vi g t - g^2 t^2 so Ke = (1/2) m v^2 = .5m [ Vi^2 - 2 Vi g t - g^2 t^2] which is a parabola with vertex at (.5 m v^2) and dropping off with time
*April 10, 2016*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html
*April 10, 2016*

**Quick Physics help**

the rope the earth it is disturbed In your book, still 20 meters In real life due to the nonlinear behavior of shallow water waves, it will experience a net drift toward shore. 25 bounces / 5 seconds = 5 Hz
*April 10, 2016*

**Physics**

u = 30 cos 60 = 15 m/s so x = 15 * 4 = 60 meters away if we are interested now vertical Vi = 30 sin 60 = 26 m/s how far up in 4 seconds? h = Vi t - 4.9 t^2 = 26(4) - 4.9(16) = 104 - 78.4 = 25.6 I get, wonder if you use 4.9 for 9.81/2
*April 10, 2016*

**statistics**

why not?
*April 10, 2016*

**Physics**

here: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html NOW, that is the power PER UNIT AREA so 3.9 *10^26 / (4 pi r^2) = power per unit area = constant*T^4 as shown in Stefan/ B link
*April 10, 2016*

**PHYSICS ENERGY CONSERVATION!!**

But, but, conservation is in your title !!!!
*April 10, 2016*

**PHYSICS ENERGY CONSERVATION!!**

at start E = (1/2) m v^2 + m g h E = (1/2)(395)(17.7)^2 + 395*9.81*7.2 = 61875 + 27900 = 89775 Joules at C 89775 = (1/2)395(7.6)^2+395*9.81*h h = [ 89775 - 11408] / (3875) h = 20.22 so agree but part b is trivial: 89775 is the total mechanical energy forever and ever by the ...
*April 10, 2016*

**factoring polynomiald**

8 b^2 + 6 b + 1 well 2+4 = 6 and 2*4 = 8 so (4b+1)(2b+1)
*April 10, 2016*

**Math**

L runs 3/5 mile/5 min = 3/25 mile/min 3 mile /3/25 mi/min = 25 min A runs7/10 / 5 = 7/50 mile/min 3 mile/ 7/50 = 150/7 = 21.4 min 25 - 21.4 = 3.6 min
*April 10, 2016*

**Math**

int (10t+1) dt = 5 t^2 + t at t = 0 that is 0 at t = x+3 that is 5(x+3)^2 +(x+3) subtract F(x) = - 5(x+3)^2 - x - 3 now do d/dx -10(x+3) - 1 or -10 x - 31
*April 10, 2016*

**science**

does pink have green?
*April 10, 2016*

**No such thing as acceleration in m/s **

-(20/3) m/s^2
*April 10, 2016*

**math**

draw the triangle
*April 10, 2016*

**science**

force = change of momentum/time = - m v /t force / area = force / given area by the way your units for first person's head area are wrong.
*April 10, 2016*

**math**

100 (80-60)/60
*April 10, 2016*

**physical science**

I guess net force includes gravity down so Force * time = change of momentum 6000 * 2.5 = 2000 (v-10)
*April 10, 2016*

**Precalculus**

AB = 6 AC = 8 all I need to know actually is AC = 8 so circumference = 8 (360/45) = 64 = 2 pi r r = 32/pi pi r^2 = pi (1024/pi^2) = 326 whatevers, miles, astronomical units, thumbs (I do physics not math)
*April 9, 2016*

**algebra**

20.5/11 = 2^n n log 2 = log 1.8636 n = .898 .898 * 6 hours = 5.39 hours
*April 9, 2016*

**Science**

F = k Q1 Q2/d^2 where k = 9 * 10^9 Q1 = Q2 = 1.6*10^-6 d = .028 meters = m g = 9.81 m
*April 9, 2016*

**cool**

Maybe there is an easier way, but that was fun !
*April 9, 2016*

**math**

log5 [ (3/5)(15^3/8) / (81/8)] well at least the 8 goes away easy log5 [ 3 *225 * 3 / 81 ] log5 [ 225/9 ] 2 log 5 (15/3) LOL !!! 2 log5 (5) 2 :)
*April 9, 2016*

**Physics**

first drop at top 0 = Vi - 9.81 t t = Vi/9.81 at top h = .55 = Vi t - 4.9 t^2 .55 = Vi^2/9.81 - 4.9(Vi^2/9.81^2) .55 = Vi^2/19.62 Vi = 3.28 m/s second drop at top .40 = Vi^2/19.62 Vi = 2.80 m/s a = (2.80 - 3.28)/time slowing down average Vi = (3.28+2.80)/2 = 3.04 m/s so time ...
*April 9, 2016*

**math, science, hindi, english, sst**

BM = MC = x which is half of BC angle AMB = T then angle AMC = 180 - T cos angle AMB = = cos T cos angle AMC = cos(180-T)=-cos T now law of cosines 4^2 = x^2 + 3^2 - 2(3x)cos T 8^2 = 3^2 + x^2 - 2(3x)(-cos T) 16 = x^2 + 9 - 6 x cos T 64 = x^2 + 9 + 6 x cos T...
*April 9, 2016*

**no, compounded**

if simple yearly interest intererst each year = .04 * 3000 = 120 120 * 10 = 1200 so 4200 would be correct BUT if compounded 3000(1.04)^10 = 3000*1.48 = 4440.73
*April 9, 2016*

**math**

times t hours and (t+2) hours) d1 = 50 t d2 = 40(t+2) 50 t = 10 + 40(t+2) 10 t = 90 t = 9
*April 9, 2016*

**math**

-2c/3 + 8 -30yz + 50 y
*April 9, 2016*

**math**

Plug and chug: numerator: f(2) = 4+3 = 7 g(7) = 3(7)- 2 = 19 f(19) = 38+3 = 41 denominator: g(2) = 6-2 = 4 f(4) = 8+3 = 11 f(11) = 22+3 = 25 so: 41/25
*April 9, 2016*