# Posts by Damon

Total # Posts: 29,823

**calc**

integrate to find x(1) and x(7) x(7)-x(1) is the displacement vector to find the distance scalar we must know when the particle is moving forward and when back and integrate over those intervals adding absolute values v = t^3 - 10 t^2 + 27 t - 18 integral = t^4/4-10t^3/3 +27t^...

**Calc**

integral of (500-3t) = 500 t - 1.5 t^2 at t = 13, integral = 500(13)-1.5(169) = 6500 - 253.5 = 6246.5 liters

**Math**

integer

**Math**

Are you sure you mean sqrt(-9) ??? That is an imaginary number. Maybe you mean sqrt (25-9) = sqrt (16) which is 4 which is a whole number and an integer

**Math**

5 + sqrt -9 5 + 3 sqt(-1) 5 + 3 i complex

**math**

m < 13 n > 13 p < 5 I think you mean at most 35 people 20 + a <= 35 a <= 15 so no more than 15

**watch units!**

watch out, km/hour given

**Calc**

a = (V2-V1)/(t2-t1) V2 = 90,000/3600 = 25 m/s V1 = 25,000/3600 = 6.94 t2-t1 = 13 so a = 1.39 m/s^2 ====================== d = V1 t + (1/2)a t^2 = 6.94 *13 + .695*169 = 208 m

**Science**

sounds right to me

**Math**

using same web site for normal dist A = .1 M = 72 sd = 9 .1 area is anything below 60.46 If I try bottom .3, anything below a C, I get A = .3 ---> below 67.28, that is the boundary for the HIGHEST D

**Math**

http://davidmlane.com/hyperstat/z_table.html area = .4 mean = 72 SD = 9 .4 are between 71.5 and 72.5 so 71.5

**physics**

total drop = 2.2+ .55 = 2.75 m drop in gravity Potential energy = = 6.95 * 9.81 * 2.75 = increase in spring Pe = (1/2)k x^2 = .5 *k * .55^2 so k = (6.95*9.81*2.75)/(.5*.55*.55)

**math algebra**

cold 1/8 tub/min hot 1/12 tub/min drain -1/7 tub/min so sum 1/8 +1/12 - 1/7 tub/min = 3/24 + 2/24 - 1/7 = 5/24 - 1/7 = 35/168 - 24/168 = 11/168 tubs/min = 168/11 min/tub = 15.3 min

**Math**

false say 1 by 1 1*1 = 1 cm^2 but 1.1 * 1.1 = 1.21 cm^2 .21 is more than .1 :)

**physics**

Ke = (1/2)m v^2 = Pe = (1/2)k x^2 (1/2)m (2v)^2 = (1/2)k (nx)^2 v^2 multiplied by 4 so x^2 multiplied by 4 so 2 times original x

**Math**

mean win = (1+2+3+0+0+0) = 6/6 = $1 so lose .25 per toss so lose $25 for 100 games

**PRE-CALCULUS**

a) 150,000 * 1.054^20 = 320,440.07 check do the others the same way as I showed you in the previous problem below

**PRE-CALCULUS**

r = .12/n where n = times per year a = 5000 * (1+r)^8n eg annual: 5000 * 1.12^8 semi where n = 2 5000 * 1.06^16 quarterly where n = 4 5000 *1.03^32 etc continuous a = 5000 e^.12 t = 5000 e^.96 = 13058.48

**Math**

3*18 = 54 m^2

**Math**

b/g = 7/9 g-12 = b so (g-12)/g = 7/9 9(g-12) = 7g 2 g = 108 g = 54 b = 42 sum = 96

**Science**

on the other hand if he carried it 500 m UP, then 100 * 500 = 50,000 Joules The problem does not say direction so who knows?

**MATH HELP!!**

Starlight Tree Farm sells Douglas firs and Noble firs. One December they sold 139 more Douglas firs than Noble firs. The total number of trees sold was 377. Which equation could be used to solve for n, the number of Noble fir trees sold

**MATH HELP!!**

You are welome

**MATH HELP!!**

25 6/25 - 20/25 = -14/25

**math**

100 times the fraction

**US History**

I guess maybe because Fort Neccessity is near Pittsburgh?

**Calculus**

delta x = .1 x range ____ y at right 1.0 to 1.1 ____ 2/1.1 = 1.82 times .1 = .182 1.1 to 1.2 ____ 2/1.2 = 1.67 times .1 = .167 1.2 to 1.3 etc in the end add them up .182 + .167 etc

**US History**

I do not think slaves were in Rhode Island before about 1700 so I agree with you. Pilgrims landed in Plymouth MA in 1620 and settlement of RI was thus later than that. I have my doubts about timing in SC as well.

**physics typo?**

Vi = 47 m/s d = 50 =============== v = Vi + a t 0 = 47 + a t a t = -47 or a = -47/t =============== d = Vi t + .5 a t^2 50 = 47 t + .5 a t^2 50 = 47 t +.5(-47/t)t^2 50 = 47 t - .5*47 t 50 = .5*47 t t = 100/47 then a = -47/(100/47)= -22 m/s^2 > twice gravity I think maybe ...

**Math**

13 = .65 x x = 13/.65 = 20

**Math**

(1/3)/5 = 1/15 but 5/(1/3) = 15

**US History**

The Spanish certainly DID find gold. They became the most powerful country in Europe for a while due to their riches from the New World. So I agree with you.

**Math algebra**

I have a hunch you mean f(x)= (x-2)/(x^2-81) which is (x-2)/ [ (x-9)(x+9) ] it is zero if the numerator is zero so when x = 2 it is undefined when the denominator is zero x = 9 or x = -9

**Math algebra**

AVA + .2*10^9 = 2 * AVE T + .6*10^9 = AVA AVA + AVE + T = 6.5*10^9 ============================ do them all in billions well T = AVA - .6 AVE = .5 AVA + .2 so AVA + .5 AVA + .2 + AVA - .6 = 6.5 2.5 AVA = 6.9 take it from there

**Math algebra**

(20+2x)(30+2x) = 936 600 + 100 x + 4 x^2 = 936 4 x^2 + 100 x - 336 = 0 x^2 + 25 x - 84 = 0 (x - 3 )(x + 28) = 0 x = 3 feet

**ANOTHER TRIANGLE MATH PROB!**

Get it?

**ANOTHER TRIANGLE MATH PROB!**

I said 12, and 12 is an option

**ANOTHER TRIANGLE MATH PROB!**

Now maybe you need to do this a more official way to really get it 21/24 = 10.5/x we want to get the 24 and the x out of the bottom so multiply both sides by 24 x 24 x (21/24) = 24 x (10.5/x) 21 x = 24 * 10.5 x = 24 * (10.5/21) x = 24 * (.5) x = 12

**ANOTHER TRIANGLE MATH PROB!**

21/24 = 10.5/x well 10.5 is half of 21 and we all know 12 is half of 24 so 10.5/12

**Physics === Not hard**

(1/2) k x^2 = (1/2) m v^2 k (.07)^2 = .0055 (11.4)^2

**physics**

Ke = (1/2) m v^2 = .5*.00335 * 255^2 in Joules = mass * heat of fusion of water = 3.35 * 333 J/gram

**Math (equation of tangent line)**

That is the second strange tangent line problem today. The first one was horizontal :)

**re: Differential Calculus**

Just copy your function into there: x^2cos^2y - siny = 0 look at the solution close to (0,0)

**re: Differential Calculus**

I mean parallel to x axis and y = pi for part 2, normal is up the y axis see http://www.wolframalpha.com/widgets/view.jsp?id=91851988c40ebbe236f5561e167c9ab8

**Math**

You are welcome.

**Math**

sqrt 15 = 3.873 3.873 * 10 = 38.73 which is about 39 so yes

**TRIANGLE HELP!!!! (MATH!)**

3/4 = 6/8 = 9/12 = 12/16 = 15/20

**math**

74 + 12*52 = 74 +624 = 698

**Tod**

Cool !

**math**

7/12 blue (12-7)/12 = 5/12 red

**Math**

(1/3) n = 5 n = 3*5 = 15 nights

**Math**

1.06 * 20.00 = 21.20

**Arithmetic**

3 for .20 is 12 for .80 so profit of .80-.70 = .10 dollars/dozen so .60 = 60 cents for 6 dozen

**Physics**

eff = Q/W = T2/(T1-T2) T2 = 26 + 273 T1-T2 = 33-26 = 7 eff = 299/7 = 42.7

**Physics**

gain in potential = m g h = 65 * 9.81 * 1100 Joules eff = ..25 so .25 energy = 65* 9.81 * 1100 so energy expended = 4*65*9.81*1100 Joules 4184 Joules = 1000 calories so in Calories (4/4.184)65*9.81*1100 power = energy expended/ time in watts = 4*65*9.81*1100/(37.5*60)

**Math**

1 2 3 4 5 6 first die 1 1 1 1 1 1 second die 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 6 total of 36 possibles the number one shows up 11 times 36 -11 = 25 times no ones 11/36 -25/36 = - 14/36 = -7/18

**not linear**

3495 *.8^t .8^5 = .328 or about $1150 which is not nothing but is also not much

**Algebra**

maybe: same as the probability that one of the numbers you choose is zero probability that first one is zero = 1/6 probability that second one is zero also is 1/6 so sum is 2/6 = 1/3

**CHEMISTRY**

try Gooling: ETHYLENE GLYCOL or antifreeze :) suspect it is Ethane-1,2-diol

**Calculus**

do the integral 4(x^2+1) dx/x^2and divide by the span which is 3-1 = 2 4 x^2 dx/x^2 + 4 dx/x^2 is 4 x - 4/x = 4 (x-1/x) at 3 = 4(3-1/3) = 32/3 at 1 = 0 so 32/3 divide by 2 16/3

**American government**

Well, if you just want my opinion as an uninvolved friend of the student, yes.

**American government**

I hope not. Read: http://www.google.com/search?q=amicus+curiae&ie=utf-8&oe=utf-8

**american government**

http://www.jiskha.com/display.cgi?id=1479316937#1479316937.1479317141

**Dynamics**

Vi = 80,000 m/3600 s a = -3.24 v = Vi + a t 0 = 80/3.6 - 3.24 t d = Vi t + (1/2) a t^2 = (80/3.6) t - 1.62 t^2

**Calculus**

(4/3)(x+3)^(1/3) but 0^(1/3) = 0 so right, zero

**Math**

x = xi - 5 y = yi + 7

**math**

b-s = 15 3 b = 8 s so b = 8s/3 8s/3 - 3s/3 = 15 5 s/3 = 15 s/3 = 3 s = 9 b = 9+15 = 24

**maths**

200 + 200 + 300 + 300 :)

**Science**

.01 * 6*10^23 * electrons per ion Do you really mean total electrons or valence electrons? If the latter it is two.

**math**

1.25^n = 2 n log 1.25 = log 2 n = log 2/ log 1.25

**Math**

(3*60/2) minutes /(1/5)minutes/pancake = 15 *30 = 450 pancakes and I do not believe you cook 5 pancakes per minute

**math**

360 = v t 360 = (v+10)(t-3) = vt -3v + 10t -30 so vt = vt -3v + 10 t - 30 10 t = 3 (v+10) but t = 360/v 3600/v = 3 v + 30 3 v^2 +30 v - 3600 = 0 v^2 + 10 v - 1200 = 0 v+40)(v-30) = 0 v = 30

**math please explain!**

You are welcome.

**math please explain!**

this is because in feet and seconds acceleration of gravity, g = 32 ft/s^2 then velocity v = Vi - g t where Vi is initial velocity and g = 32 ft/s^2 and height h is h = Hi + Vi t - (1/2)g t^2 in this problem h = Hi + Vi t - 16 t^2 where Hi = 20 and Vi = 120

**math please explain!**

h = 20 + 120 * 3 - 16 (9) = 20 + 360 - 144 in feet where g = 32 ft/s^2

**The Maths**

multiply second equation by -1 then add +4x + 3y = -2 -4x + 4y = 16 ---------------add 0 + 7 y = 14 so = +2

**Math**

diameter = twice the radius

**Science**

v = Vi + a t v = 10 + 2.5 t 40 = 10 + 2.5 t t = 30/2.5 x = vi t + (1/2) a t^2 = 10 t + 1.25 t^2

**Maths**

weight of dog at time t how much weight the dog gained between those times

**Math**

60/4 = 15

**Calc**

well the integral is x^4/4 + C Now in between x = 0 and x = 3 the slope of the integral must be f(0) = 0 f(3) = 27 so the integral must be between 0 + 0(3) = 0 or 0 + 27*3 = 81 In fact the integral is 3^4/4 = 81/4 or about 20

**science**

v = Vi + a t v = 0 + 2 (3.2) = 6.4 m/s

**Math**

(x+25)/2 = 3 x

**Science**

Flat , perpendicular hard walls, ceilings and floors are a no-no. Use heavy carpets, hanging heavy fabric, and soft ceiling tile. Break up the flat perpendicular surfaces with nooks and crannies and odd angles and big furniture. Use soft seating in an auditorium. You can get ...

**Chem**

.065 = .15 x + .01 .15 x = .055 x = 5.5/15

**geography**

I am inclined to say Google it but you get a barrage of propaganda. With the Balfour Declaration the English opened the eastern coast of the Mediterranean Sea to settlement by Jewish immigrants. That was kind of them but ignored the fact that people, namely Palestinians, ...

**Algebra2**

You are welcome.

**Algebra2**

(x+1)(x-3)(x-3) = 0 Three real roots single real at x = -1 double real at x = 3 http://www.wolframalpha.com/input/?i=solve+x%5E3+-5x%5E2+%2B+3x+%2B+9+%3D+0+%3D+0

**algebra**

one worker paints 400 meters in 5 hours so one worker does 80 meters/hour 80 m/wh * 4 w * 2 h = 640 m

**Math**

a^2 + b^2 = 36 a + b + 6 = 14 so a = 8-b 64 - 16 b + 2 b^2 =36 2 b^2 - 16 b + 28 = 0 b^2 - 8 b + 14 = 0 b = [ 8 +/- sqrt (64 -56) ]/2 b = [ 8 +/- 2sqrt 2 ]/2 b = 4+/-sqrt 2 if b = 4+sqrt 2 a = 4 - sqrt 2 A = (1/2)ab = (1/2)(16-2) = 7 m^2

**math**

b + 2 b = 1500 3 b = 1500 b = 500

**math**

14.0 - 6.7 = 7.3

**physics think typo in speed**

v = Vi + a t 12.5 = 226 + a t so a = - 213.5/t d = Vi t + .5 a t^2 105 = 226 t - .5 * 213/t * t^2 105 = 226 t - 106.5 t t = .879 seconds a = -213/.879 = -242 m/s^2 you can do the rest but suspect you have a typo

**physics**

conservation of momentum in N/S and in E/W directions. Initial momentum is zero.

**Hey, one is enough**

I already did one like this below.

**physics**

total mass = .14 +.47 = .61 kg weight = .61*9.81 friction force = .5 * .61 * 9.81 work done = force * distance = .5*.61*9.81*6.8 so (1/2)(.61) v^2 = .5 * .61 * 9.81*6.8 where v is initial speed of can with pellet v^2 = 9.81*6.8 solve for v now conservation of momentum u is ...

**physics**

get speeds from conservation of momentum 93 g = 60 v 15 g + v t = 83 15 g = 83/2 --------------- so -------------- g = 83/30 = 2.77 v = 93/60 *83/30 = 4.29 v t = 41.5 t = 9.67 seconds check 9.67 * 4.29 = 41.5 15 * 2.77 = 41.55 v/g = 4.29/2.77 = 1.55 93/60 = 1.55 ok

**Science**

v = Vi - g t = 15 - 9.81 (.5) = 10.1 m/s h = Vi t - 4.9 t^2 = 15 (.5) -4.9(.25)

**Physics**

3.70 v + 4.70 (8) = (3.7+4.7)(15.6)

**I do not know**

If you fired it straight up, the truck would not move. If you fired it straight back and there were no brakes on the truck then 53.8 (41.7) = (856-53.8) v