Tuesday

May 24, 2016
Total # Posts: 26,278

**Math**

Hey- you can do that ! x-2 = 0 so x = 2 x-3 = 0 so x = 3 x+3 = 0 so x = -3
*January 29, 2016*

**Algebra 2**

boring ! x-4y-6z=-34 times 5 -7x+5y-7z=-24 times 4 +5 x -20 y - 30 z = -170 -28x +20 y - 28 z = -96 --------------------------add -23 x + 0 -58 z = - 266 now the last 2 -7x+5y-7z=-24 times 7 +5x-7y-1z=-18 times 5 -49 x + 35 y - 49 z = -168 +25 x - 35 y - 5 z = -90...
*January 29, 2016*

**Algebra 2**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx I get (4, 5, 3)
*January 29, 2016*

**Algebra 2**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*January 29, 2016*

**Math**

y = 4 - x x^2 + (16 - 8 x + x^2) = 16 2 x^2 - 8 x = 0 x( 2x-8 ) = 0 x = 0 or x = 4 y = 0 or y = 4 of course, symmetry :) (0,4) or (4,0)
*January 29, 2016*

**Math**

You are welcome.
*January 29, 2016*

**Math**

y = a x^2 + b x + c 12 = a (1) + b(-1) + c 5 = a(0) + b(0) + c so c = 5 15 = a(4) + b(2) + 5 7 = a - b so a = b + 7 10 = 4 a + 2 b 10 = 4(b+7) + 2 b 10 = 4 b + 28 + 2 b 6 b = -18 b = -3 then a = b+7 = +4 so y = 4 x^2 - 3 x + 5
*January 29, 2016*

**mistake in division**

assuming the first 5 x = 3 x + 6 2 x = 6 x = 3
*January 29, 2016*

**Geometry**

Do you mean: x/3 = (x+2)/5 or x/3 = x + 2/5 ? assuming the first 5 x = 3 x + 6 2 x = 6 x = 2 assuming the second (which you wrote) x/3 = 3x/3 + 2/5 5 x = 15 x + 6 -10 x = 6 x = -3/5
*January 29, 2016*

**math**

You have to give us some dimension, like how far away
*January 29, 2016*

**Physics**

G M1 M2 / 19^2 6.67 * 10^-11 (1.45*10^4)(6.4*10^3) / 361
*January 29, 2016*

**mathematics**

I am not telling. Look at: http://www.mathsisfun.com/associative-commutative-distributive.html Hint - it starts with A
*January 29, 2016*

**Quick calc question**

calc question? LOL s(4) = 4*16 + 4 = 68 miles s(1) = 5 miles distance traveled = 63 miles time = 4 - 1 = 3 hours av speed = 63/3 = 21 miles/hour
*January 29, 2016*

**Quick calc question**

dy/dx = 2 + 4 cos 4 x so cos 4x = -1/2 4x = 180 - 60 degrees = 120 degrees = (2/3) pi so x = pi/6 or 4x = 180+60 or 4 pi/3 so x = pi/3 4 x = 360+180 - 60 = 480 =8 pi/3 so x = 2 pi/3 4 x = 360+180 + 60 = 600 = 10 pi/3 so x = 5 pi/6 too big so pi/6 , pi/3 , 2 pi/3
*January 29, 2016*

**Physics**

(1/2) a t^2
*January 29, 2016*

**No idea**

What ? what is the function ? Use parentheses if needed.
*January 29, 2016*

**Math**

15/2 is 7.5
*January 29, 2016*

**Science**

Yes, that is the only chemical reaction on your list.
*January 29, 2016*

**PHYSICS**

There is a direct answer? Please post it if you find it.
*January 29, 2016*

**Physics help**

http://www.jiskha.com/display.cgi?id=1454030373
*January 28, 2016*

**Physics help**

I have done #4 several times
*January 28, 2016*

**Physics help**

V2n = 1.20 V2e = -.00155 v = sqrt (1.2^2 + .00155^2) or about 1.2 and about North Yes, we agre Hey I am not going to do all these. You have the idea
*January 28, 2016*

**Physics help**

call m = 1 since they are the same Initial momentum N = V2n + 0 Initial momentum E = V2e + 0 final momentum N = 1.25cos44 + .92 cos 71 final momentum E =1.25sin44 -.92sin71 so V2n = 1.25cos44 + .92 cos 71 V2e = 1.25sin44 -.92sin71
*January 28, 2016*

**please use same name**

http://www.jiskha.com/display.cgi?id=1454030373
*January 28, 2016*

**oh my**

4. initial momentum N = 1800 Hey, I just did this
*January 28, 2016*

**Algebra 1**

1. geometric series a r^(n-1) a = .5, r = -2 .5 *(-2)^(n-1) 2. same deal 5 *(-1/3)^n-1 and on and on .....
*January 28, 2016*

**college**

I suspect that the proposed developer EMPLOYS only .....
*January 28, 2016*

**Physics help**

north momentum before = 1800*22 east momentum before = 3200*14 north momentum after = 5000 Vn east momentum after = 5000 Ve so Vn = 1800*22/5000 Ve = 3200*14/5000 v = sqrt (Vn^2 + Ve^2) tan angle east of north (compass heading) = Ve/Vn
*January 28, 2016*

**before you type any more,**

Go back and understand the ones Bob and I have done.
*January 28, 2016*

**maths/physics**

F = G M1 M2/r^2 dF/dr = G M1 M2 [ -2 r /r^4 } = - G M1 M2 (2/r^3)
*January 28, 2016*

**maths/physics**

V = (4/3) pi r^3 dV/dr = (4/3) 3 pi r^2 dV/dr = 4 pi r^2 OF COURSE this is the surface area of the sphere, see why?
*January 28, 2016*

**Physics (**

m = mass = rho * (4/3) pi r^3 A =cross section area = pi r^2 m/A = rho * (4/3) r d/dr (m/A) = (4/3) rho NOTE DISAGREE I guess the density of your sphere is one? Vt is when m g = C * p (1/2)Vt^2 A Vt^2 = 2 m g /(pCA) Vt = [2 m g /(pCA)]^.5 let MA = m/A then Vt = [2 g/pC]^.5 [ m...
*January 28, 2016*

**Physics (**

LOL - she sure has tough ones. It took me a while to figure out the landing on an optimal radius plant one.
*January 28, 2016*

**Well, you asked for it :)**

CHECK THAT ARITHMETIC ! I think you can get the picture from what I did but I did it fast.
*January 28, 2016*

**Physics (Gravitation)**

v = sqrt [ 2 G M/r ] v = [ 13.6 *10^-11 (10^22+r^4)/r]^.5 form is v = [ k (a+r^4)/r ]^.5 we want where dv/dr = 0 0 =dv/dr = .5 k^.5[ (a+r^4)/r ]^-.5 * [r (3 r^3)- (a+r^4)] /r^2 luckily that is zero when [r (3 r^3)- (a+r^4)] = 0 3 r^4 - r^4 = a 2 r^4 = a r^4 = a/2 but a = 10^22...
*January 28, 2016*

**Pre-calc**

Boat A east: x = 13 t Boat B north y = 20 (t-1) d = sqrt (x^2+y^2) d = sqrt [169 t^2 + 400 (t^2-2 t +1) ] d = (569 t^2 -800 t + 400 )^(1/2
*January 28, 2016*

**World History**

How much do we count slaves when figuring how many representatives a state gets in congress these day? When was it legal to drink alcohol? When was it not? What about the entire Bill of Rights, the first ten Amendments to the constitution? Have we always had an income tax? How...
*January 28, 2016*

**Math**

ds/dt = 14 t if t = 7 14 * 7 = 98
*January 28, 2016*

**Math**

58/62 = x/100 x = 93.54 % which rounds to 93.5 %
*January 28, 2016*

**algebra**

I do not understand the problem. If the bridge is 20 feet across the cut, it will stick up 20 feet when you raise it 90 degrees.
*January 28, 2016*

**Math**

The real question is: 33/88 = x/100
*January 28, 2016*

**Math**

33*100/88 = 37.5 % You did it right but to get percent from fraction multiply by 100 and your arithmetic is wrong. 33/88 = .375
*January 28, 2016*

**Ihave about ten times no C in NaCl**

Na = sodium Cl = chlorine no C, carbon
*January 28, 2016*

**Science**

I suspect that you could separate these by distillation
*January 28, 2016*

**Math**

coin 1 **h t coin 2 h 6 4 coin 2 t 4 0 p(6 points) = 1/4 p(4 points) = 1/2 p(0 points) = 1/4 (1/4)6 + (1/2)4 = 2 + 1.5 = 3.5 so I agree with you
*January 28, 2016*

**Physics**

weight = 2 * 10^3 * 9.81 = 19.62*10^3 N mechanical advantage = .75/.005 = 150 (19.62/150)* 10^3 = 130.8 N
*January 28, 2016*

**Science**

salt only has sodium (Na) and Chlorine (Cl) They are however both compounds which are held together by chemical bonds.
*January 28, 2016*

**physics**

10 protons * 1.6*10^-19 C per proton = 16*10^-19 C per atom 16*10^-19 C/atom * 6*10^23 atoms/mol = 96*10^4 C/mol 96*10^4 C/mol * 1 mol/20.2 g = 4.75*10^4 C/gram 4.75*10^4 C/gram * 800 grams = 3801*10^4 = 3.8 *10^7 C Luckily the neutral atoms have an equal number of electrons ...
*January 28, 2016*

**physics**

Oh k is about 9*10^9
*January 28, 2016*

**physics**

F = m a = k Q1 Q2/d^2 so a = F/m m = 27 g = .027 kg Q1 = 32*10^-6 Q2 = -22*10^-6 so F is attractive between them F=(1/.027)k (32)(22)(10^-12)/.79^2
*January 28, 2016*

**physics**

F = k Q1 Q2 / d^2 = 9*10^9 (46)(46)/(36*10^6)
*January 28, 2016*

**Science**

Na = sodium Cl = chlorine no C in there
*January 28, 2016*

**physics**

T = 20.6/4 = 5.15 seconds period between crests wave goes 2.97 m in 5.15 seconds speed of crest = 2.97/5.15 m/s frequency = 1/T since you did not include a question, I am guessing that is what you want
*January 28, 2016*

**Calculus**

ln [(x+1)/(x-1)] = 2 (x+1)/( x-1) = e^2 = 7.39
*January 28, 2016*

**maths science and geography**

a r^4 = 4 a r^2 r^2 = 4 r = +/- 2 -2
*January 28, 2016*

**Maths - Differentiation**

4 x^2 y = 64 so y = 16/x^2 I guess it has a square bottom and height y Area = area top and bottom + 4 x y = 2*4 x^2 + 4* 2 x y = 8 x^2 + 8 x y = 8 x^2 + 8 x (16/x^2) = 8 x^2 + 128/x agreed dA/dx = 16 x -128/x^2 = 0 at max or min 16 x^3 = 128 x^3 = 8 x = 2 c) d^2A/dx^2 = 16 +...
*January 28, 2016*

**history .**

I would say fear and anger
*January 28, 2016*

**Maths - Differentiation**

C) the function graph is horizontal when dy/dx = 0 (1/16) x^2 -1/x^2 = 0 (1/16) x^4 = 1 x^4 = 16 x = + or - 2 D) at x = -2 d^2y/dx^2 = (1/8)(-2) +2(1/-8) negative so headed down, a maximum at x = + 2 POSITIVE SO HEADED UP, MINIMUM
*January 28, 2016*

**Math**

7*100 + 16*10 + 3 700 + 160 + 3 800 + 60 + 3 863
*January 28, 2016*

**Mathematics**

a = (2/3) b + 1/3 use in eqn 2 3 b = 5 [(2/3) b + 1/3 ] - 3 3 b = (10/3)b + 5/3 - 3 9 b = 10 b + 5 - 9 b = 9-5 b = 4 3a = 2(4) +1 = 8+1 a = 3
*January 28, 2016*

**Science**

1. yes 2. yes 4. yes 5. yes 6. yes 7. yes 8. yes 9. yes 10. I would say boiling and evaporating since they are really the same. I am not sure you can filter dissolved sugar out of water except perhaps by reverse osmosis
*January 28, 2016*

**Calculus**

inverse would be time for a specific population 1+749 e^-.15t = 7500/p 749 e^-0.15 t = (7500-p)/p e^-.015 t = (7500-p)/(749 p) e^.015t = 749 p/(7500-p) .015 t = ln [ 749 p] - ln [7500-p)] t = 66.7 [ln 749 p - ln(7500-p)] we had 10 when t was 0 so check t = 66.7[ ln 7490 - ln ...
*January 28, 2016*

**Pre-calculas**

Is the point at the bottom or the top? whichever way you draw it Volume of a cone = (1/3)pi R^2 x where r is the radius of the surface and x is distance from the tip r/x = 9.5/ 16 = .594 so r = .594 x v = (1/3) pi (.594x)^2 x v = .369 x^3 dv/dx = 1.11 x^2 dv/dt = 1.11 x^2 dx/...
*January 27, 2016*

**Math**

yes, only one that has angles less than 90 and adds to 180
*January 27, 2016*

**physics**

Vi = initial speed up u = constant horizontal speed find t, time in air Vi = 135 sin 18.3 = 39.25 u = 135 cos 18.3 = 128.2 d = u T find T the time in air v = Vi - 9.8 t at top where v = 0 and t=T/2 0 = 39.25 - 9.8 t t = 4.005 s so T = 2 t = 8.01 seconds in the air d = u t = ...
*January 27, 2016*

**Math**

1700 * 100 / 8500 = 20 %
*January 27, 2016*

**Algebra**

n n+2 n+4 n+6 ---- 4 n + 12 = 80 4 n = 68 n = 17 17, 19 ,21 ,23
*January 27, 2016*

**Math**

make a sketch !!! a diagonal would for example be from B to D change in x = 1 - -1 = 2 change in y = -3 - +3 = -6 sqrt (2^2+6^2) = sqrt 40 = 2 sqrt 10
*January 27, 2016*

**Algebra**

n + n+2 = 1306 2 n = 1304 n = 652 n+2 = 654
*January 27, 2016*

**Math**

Agree, only one with all less than 90 and adds to 180
*January 27, 2016*

**Math**

Remember 40% LOSS is 60% LEFT :)
*January 27, 2016*

**Math**

.6 * 300 = 180 left after 40% trim .4 * 180 = 72 left to eat
*January 27, 2016*

**math**

You are welcome.
*January 27, 2016*

**math**

1.03^10 = 1.344 times 19900 = 26744 You got it
*January 27, 2016*

**Algebra**

n + n+1 + n+2 3 n + 3 = 930 3 n = 927 n = 309 and 310 and 311
*January 27, 2016*

**English**

because gh is two consonants http://www.howtospell.co.uk/doubling-up-rule
*January 27, 2016*

**Physical Science**

Yes, assuming electromagnetic (not water or sound or whatever)
*January 27, 2016*

**Math**

(200/5000)100 = 20000/5000 = 20/5 = 4%
*January 27, 2016*

**Algebra**

n + n + 1 = 529 2 n = 528 n = 264 n+1 = 265 add them to check
*January 27, 2016*

**math**

total rise = 112 - 149 = -37
*January 27, 2016*

**math**

you have 12 girls put one girl and 3 boys in each of 12 groups
*January 27, 2016*

**Math**

4n+2 = 14 ? 4 n = 12 n=3 2n = 6 2n+2 = 8
*January 27, 2016*

**physics**

Rx = 15 cos 250 = -5.13 m Ry = 15 sin 250 = -14.1 m ============================ new one is - 2 times old 250 - 180 = 70 degrees is opposite Rx = 30 cos 70 = 10.3 Ry = 30 sin 70 = 28.2 R^2 = (Rx^2+Ry)^2 = 30^2 (sin^2+cos^2) = 30^2 so it is 30 of course direction is the old ...
*January 27, 2016*

**physics**

I rounded .115 to .12 in part a (as instructed :) If they use 4.9 (1.15)^2 they would get 6.48 which rounds to 6.5
*January 27, 2016*

**physics**

t = distance/speed = .115 * 10^-6 seconds which is 1.2 *10^-7 seconds h = (1/2) g t^2 h = 4.9 (1.44)(10^-14) h = 7.1 * 10^-14 meters
*January 27, 2016*

**Physics**

F = k Q1Q2/r^2 here r = .115 so let (k/r^2) = c constant Fnorth = -(3.17*3.96*10^-12)c Feast = +(3.17*5.03*10^-12)c magnitude = sqrt (Fx^2 + Fy ^2)
*January 27, 2016*

**Physical Science**

solids are harder to squish. look here: https://www.khanacademy.org/science/physics/mechanical-waves-and-sound/sound-topic/v/relative-speed-of-sound-in-solids-liquids-and-gases
*January 27, 2016*

**physics**

C runs 4.09 t meters C runs 4.28 t meters 4.28 t - 4.09 t = 94
*January 27, 2016*

**les/math**

original box x (2x)(5x) = 80 x^3 = 8 so x = 2 2x = 4 5x = 10 now new box 4 * 6 * 12 = 288 cm^3 increase = 288 - 80 = 208
*January 27, 2016*

**physics**

1490 + 25,000 tan 2.6 = h h = 1490 + 1135 h = 2625 meters
*January 27, 2016*

**Math**

Yes, could have any old value, including the same.
*January 27, 2016*

**math**

h * 6 = 102 h = 102/6 = 17 17 what though? inches,feet meters? decimeters? elbows? miles? kilometers? Is Rita a doll or a dinosaur?
*January 27, 2016*

**Physics**

- (1.2*10^4 )(1.6*10^-19) = 1.9 *10^-15 C = 1.9 * 10^-9 µC
*January 27, 2016*

**math**

a taxi ride costs 5 dollars to start the meter and then 4 dollars per mile. I have 37 dollars. How far can I ride? ( I guess I will not leave a tip :( 4 x = 37 - 5 4 x = 32 x = 8 miles
*January 27, 2016*

**Math**

ln(2x+3)^4 = 11 e^ln(2x+3)^4 = (2x+3)^4 = e^11 (2x+3) = (e^11)^.25 = e^2.75 = 15.64 2x = 12.64 x = 6.32
*January 27, 2016*

**Math**

Hey Rita, read what you wrote. We have no idea what your scale ratio is hint ratio of areas = ratio of lengths^2 2/1 in length is 4/1 in area (and 8/1 in volume)
*January 27, 2016*

**history .**

I agree with A for both. However I am not a history teacher.
*January 27, 2016*

**Math**

Log2(x)+log2(x-3)=2 2^[Log2(x)+log2(x-3)] =2^2 2^log2(x^2-3x) = 2^2 (x^2-3x) = 4 x^2 - 3 x - 4 = 0 (x-4)(x+1) = 0 x = 4 or x = -1
*January 27, 2016*

**Math**

2log6(4x)=0 log6 (16 x^2) = 0 6^log6 (16 x^2) = 16x^2 = 6^0 = 1 so x^2 = 1/16 x = 1/4 normally I would say also -1/4 but try to take the log of -1 :)
*January 27, 2016*