# Posts by Damon

Total # Posts: 29,990

**Maths**

alpha^.5 = [b +sqrt(b^2-4c)]/2 beta^.5 = [b -sqrt(b^2-4c)]/2 alpha =(1/4) [ b^2 +2bsqrt(b^2-4c)+b^2-4c] beta =(1/4) [ b^2 -2bsqrt(b^2-4c)+b^2-4c] alpha + beta = (1/4) [4 b^2 -8 c] = b^2 - 2 c etc ....

**physics**

10^4 km = 10^7 meters !!!! well the force on 1kg is the value of g there :) F = G * 1 * M /R^2 F =6.67*10^-11 * 6 *10^6 /(16*10^14) I think you probably have a typo

**Math**

-5 = -a+b-c dy/dx = 3 a x^2 + 2 b x + c = 4 at x = -1 so 3a - 2b + c = 4 d^2y/dx^2 = 0 = 6ax +2b = -6a+2b so b = 3 a 3 a -6a + c = 4 -5 = -a +3a -c -3a + c = +4 +2a - c = -5 ------------ 5 a = 9 etc check my arithmetic

**Math Independent & Dependent.**

the cost depends on how many c = 7 s http://nces.ed.gov/nceskids/help/user_guide/graph/variables.asp

**Calculus unit review**

draw a graph point A is (1/11) f(5) = f(1) + integral 1 to 5 (f' dx) = 11 + 9 = 20 or just say integral from 1 to 5 of (dy/dx) dx = y(5)-y(1)

**Math**

before x students 5x/8 boys and 3x/8 girls so later 3x/8 + 6 = 5x/8 3 x + 48 = 5 x 2 x = 48 so x = 24 students before x+6 = 30 after 6 girls arrived

**how many minutes**

hours = minutes/60 speed = 63 miles/those hours

**math**

1.20 x

**Math**

(7/8)(16/1) = 7*16/8 = 7*2 = 14

**Math**

hat is zero at -3, -3 , 2 ,2 , -5 the double roots mean the curve just touches the axis at: -3 and +2 when x is big positive, it is big positive when x is big negative it is big negative y = 180 when x = 0 so starts at lower left crosses x axis at x=-5 goes up then dips down ...

**Physics**

total energy is constant until it hits the ground. Potential turns to kinetic. m g h = 8 * 9.81 * 100 Joules

**History**

I am inclined to agree with you. See: http://en.wikipedia.org/wiki/Freedmen's_Bureau_bills although in practice it turned out more like B and even that was undermined by the KKK etc.

**Math - limits**

in radians sin t --> t + t^2/2! -t^3/3!..... so in radians sin t/t --->1 as t--->0 however we are doing degrees do t degrees which is (pi t/180) rad so we have sin (pi t/180) /t which becomes (pi t/180 +(pi t/180)^2/2 ... divided by t ----> pi/180 as t--->0...

**Math**

15/12 = 5/4

**Math**

agree

**Math**

1 / 3

**math**

Smith: 1 teen drinks 2/3 case / 5 weeks so 1 teen drinks 2/15 case / 1 week ===============================Jones 1 teen drinks 5/6 case / 4 weeks so 1 teen drinks 5/24 case / 1 week ======================== smith 2/15 jones 5/24 which is bigger? 15 = 3*5 24 = 3 * 8 3*8*5 = 120...

**math**

Once again 192 - 150 = 42 NOT 142

**Social studies**

ok :) Then I agree with you.

**spelling ?**

mass crowding maybe? If so yes.

**error**

192=k+54c............................. (1) 150=k+14c. ........................... (2) subtract (1) from (2) 142=40c ============================= whoops 42 not 142

**physics**

mg + mv^2/r = 1000 Newtons g = 9.81 m/s^2 v = 7.4 m/s r = 11.2 m solve for m

**statistics**

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

**Physics**

yes, true power = V i but V = i R so Power = i^2 R = V^2/R Joules per second or "Watts" Energy (or heat) = Power * time so indeed H = i^2 R t = V^2/R Joules Now how much heat do we need? H = mass * specific heat * change in temp H = 0.5 * 4.19*10^3 * 70 Joules so in ...

**Science**

x = sin (2 pi t/T) 1/2 = sin (2 pi t/24) 2 pi t/24 = pi/6 because pi/3 radians= 30 degrees and sin pi/6 = 1/2 t/12 = 1/6 t = 2

**Math**

L = 31.5 w = (4/7)31.5 = 18 p = 2 * 31.5 + 2 * 18 A = 31.5 * 18

**Science**

force = change in momentum/time 10 N = 10 kg *V / 10 s V = 10 m/s ============= or F = m a 10 = 10 a a = 1 m/s^2 v = a t v = 1*10 = 10 m/s

**physics**

v = a t 100 m/s = a ( 5 s) s = 20 m/s^2

**Physics**

By the way, GOOGLE Archimedes

**Physics**

weight in water = WW Newtons weight in air = WA Newtons mass = WA/9.81 kilograms (if your scale reads in kilograms, multiply by 9.81 m/s^2 on earth to get Newtons) difference = WA-WW = buoyant force = volume*density of water * 9.81 density of water = 1,000 kg/m^3 so difference...

**algebra**

typo maybe?

**algebra**

you have 0k so you can not solve for k

**physics**

a = dv/dt = 6.24 so v = constant + 6.24 t at t = 0, v = Vi so v = Vi + 6.24 t 9.36 = Vi + 6.24 * .44

**Math**

think ! 1. It starts in 1990 at 1,000,000 2. it DECREASES and you meant to the POWER t, not times t a k^t not a k t to check at 2010, t = 20 years y = 1,000,000* .98^20 ?

**order does matter, typo by me**

Write the number of permutations in factorial form, then simplify. How many differnet ways can you and four of your friends sit in the backseat of a limousine? A. 4!;24 b.4!120 C.5! 120 D. 5! 720 There are 5 of you. Order does matter so permutations of 5 taken 5 at a time 5! =...

**PLLZ!PLLZ help with math quick!!!!!**

Ariel wants to choose 5 players for her basketball team. There are 7 players to choose from.How many different teams can Ariel make? A. 21 B.32 c.42 D.56 =============================== combinations in grade seven? C(n,r) = n!/[r!(n-r)!] = 7!/[5!(2!)] = 7*6/2 =21...

**enough already**

I already answered most of these.

**Math**

24 x^2 = 3*4.5 = 13.5 x^2 =13.5/24 so x^2 = .5625 feet^2 *144 in^2/ft^2 = 81 inches^2 so 9 inches on a side

**Algebra**

sketch graph at x = -oo it goes to -oo at x = -1 it is +6 at x = 0 it is-2 at x = +oo it is +oo SO it crosses the x axis three times, three real roots

**Math PROBABILITY part 1**

3/36 = 1/12 are less than 4 1,1 1,2 2,1 ================== IF you mean < or = 4 THEN 6/36 = 1/6

**Math PROBABILITY part 1**

1 though 6 horizontal and 1 - 6 verrtical chat 36 possible rools 9 have up two odd 9/36 = 1/4 so I bet B

**Math PROBABILITY part 1**

4/9 + 7/18 + x = 18/18 15/18 + x = 18/18 x = 3/18 = 1/6 which is a

**Math PROBABILITY part 1**

yes, 5/8 yes 4/9 next, problems

**PHYSICS**

1.3*.4 = .52 .7*.4 = .28 total distance = .8 total time = 1.1 av speed = .8/1.1 = .73 m/s

**math plzzz help quick**

You are welcome.

**math plzzz help quick**

2x = y-14 so -4x = -2(y-14) = -2y + 28 use that for -4x in equation 2 (-2y+28) - y = 4 -3 y = -24

**physics**

Vi = 14 a = -3.3 v = Vi + a t at stop, v = 0 0 = 14 - 3.3 t 3.3 t = 14 for half time if t = 7/3.3 v = 14 - 3.3 (7/3.3) v = 14 - 7 = 7 on the nose then

**math plzzz help quick**

rewrite first one x = y -11 use that for x in the second one y + 7 = -2(y-11) y + 7 = -2 y + 22 3 y = 15 y = 5

**Algebra**

divide by factor (x+2) (x^3 – 3x^2 – 6x + 8)/(x+2) = x^2-5x+4 which is (x-4)(x-1) so 4 and 1

**electricity**

15 = 60R/(60+R) 900 + 15 R = 60 R 45 R = 900

**Physics**

m v^2/R = 600 0.8 v^2/0.9 = 600

**modern worl studies connexus**

6 NO WAY!!! 9 Canada has its own monarch ??? First I heard of it, and I row against them up there in Nova Scotia.

**math**

4 works for 1, 4 or 4 people 6 works for 1, 2 , 3 or 6 people

**math**

READ That was the CHECK James is 48

**math**

Jo + 5 = Ja/3 Jo - 3 = Ja/6 -------------- subtract 0 + 8 = Ja(1/3 - 1/6) Ja (2/6-1/6) = 8 Ja = 6*8 = 48 =========================== check Ja = 48 Jo = 3 + Ja/6 = 3 + 8 = 11 then 11+5 = ??? 48/3 16 = 16 sure enough

**need info**

Please type entire problem. Without knowing the density of the logs or the mass of you and your friend, no way. call log density rho call g = 9.81 m/s^2 water density = 1000 kg/m^2 mass of passengers = m n = number of logs n * .13^2 *2.2 = V, needed volume of logs 1000 g V = B...

**mechanics**

F1 = f in x direction F2 = f cos 60 in x and f sin 60 in y total x = f +f cos 60 = 1.5 f total y = f sin 60 = [sqrt3/2]f magnitude of resultant = sqrt [ 1.5^2 f^2 + 3/4 f^2 ] = f sqrt [2.25 +.75 ] = f sqrt 3

**Phycis**

(1/2 )m v^2 + m g h = 1470 so Ke = 1470 - m(9.81)25 to get a numerical answer you need to know m

**Physics**

with constant acceleration a: v = Vi + a t x = Xi + Vi t + (1/2) a t^2 here Vi = Xi = 0 so x = (1/2)at^2

**math**

Fid = Fif + 26 Fif = R-12 so R = Fif+12 Fid + Fif + R = 71 Fif+26 + Fif + Fif+12 = 71

**physics**

2.2*10^4 = mg + ma =2150(9.81+a)

**Calculus**

http://www.jiskha.com/display.cgi?id=1486194050

**value**

75/3 = 25

**distance ?**

You have to know some distance in the problem. Otherwise you just have similar triangles of arbitrary size.

**maths**

well, go ahead. 30, 60, 90 triangle side opposite 30 = 5.6 sin 30 side opposite 60 = 5.6 sin 60

**Calculus**

tangent of angle above x axis = 35/42 magnitude = sqrt (42^2+35^2)

**Math**

0 to 9

**Physics**

F = G Mm m /Rm^2 F/m = G Mm/Rm^2 = 6.67×10-11 m^3 kg-1 s-2 * 1.08*10^16kg/[1.35*10^4]^2m^2

**history**

No way !

**Math**

4/-2 = -2 -2/-2 = 1 1/-2 = -1/2 (-1/2)/-2 = 1/4

**math**

(35/64)a = 2450 a = 2450*64 /35

**Math : ratio and proportion**

(2 L/80km) 1 km = 1/40 liter

**Geometry**

north wind due to boat speed at 16 kn west wind at 10.4 kn magnitude = sqrt(16^2+10.4^2) tan angle west of north = 10.4/16 compass angle= 360 - that angle

**Math**

5 * .0625 * 7150 = interest due total = interest due + 7150

**Mathmaybe something like:s**

7 , 8, 9 , 11 , 11, 11

**MS. SUE! World History (Absolutism and Revolution)**

The second one, Peter the Great's accomplishments,is correct. Do not forget he established a Russian port, called St. Petersburg, on the Baltic. I do not know much about Maria T. However from what little I know I would vote for #3.

**History**

http://www.britannica.com/event/United-States-presidential-election-of-1860

**History**

10 a is correct 3 see http://www.carolana.com/SC/1800s/antebellum/educational_opportunities.html 7. D is correct 8. http://www.geni.com/projects/Southern-Fire-Eaters/4715 9. Good grief, no slavery did not become legal in Massachusetts. However in theory after that decision, a ...

**Maths**

two years at 3% = .03*2 = .06 so .06 times original deposit = 72 so 72/.06 which is 1200

**Maths**

.06 v = £72

**C**

Sometimes: "Code of Ethics"

**dynamics**

v = -k ln x + c 15 = -k ln .6 + c 9 = -k ln 1.2+ c -----------------subtract 6 = -k ln(.6/1.2) etc

**Math m1**

600 = 400 a so a = 600/400 total force = 400 a + 1000 a = 1400 a

**physics**

and add heat of vaporization to steam

**Geologic Time and Earth's History Unit Te**

I would be happy to do it but need WhiteRain's text book.

**ah --**

hey - only the component in the k direction passes through your loop :)

**set maths**

You have to do this with a Venn diagram, which I can not really draw here but using that you should be able to figure it out.

**So where is your work?**

So where is your attempt to do this? There are two common ways, I do not even know which you are using since I see no work.

**History**

1. agree 2. agree 3. agree 4. agree Hey, you know the answers perfectly well :)

**Math--Matrix**

http://matrixcalc.org/en/vectors.html

**Math--Matrix**

http://www.sosmath.com/matrix/eigen1/eigen1.html

**physics**

Newtonian Gravity, objects of mass M and n: F = force of attraction on each F = G m M/r^2 if M is earth mass, call it Me and r is earth radius, call it Re then G Me/Re^2 = 9.81 m/s^2 approximately so F = 9.81 m F/m we call acceleration of gravity on earth, g = about 9.81 If ...

**physics**

now F = m g work done against gravity = integral F*dr or m g dr or m * integral g dr m 9.8 Re^2 integral dr/r^2 from Re to 4 Re integral dx/x^2 = -1/x so here 1/6,400,000 - 1/25,600,000 = 1.17 * 10^-7 so work done in Joules - m 9.8 Re^2 * 1.17* 10^-7 = m (47,040,000) Joules ...

**trick question**

Although g may be about 9.8 m/s^2 at the surface of earth, it is not 9.8 at 4 Re and therefore you can not assume it is constant g = 9.8 (Re^2/r^2)

**calculus**

yes

**backwards**

sorry P(0 broke) = 1* 1 * .82^11 P(1 broke) = C(11,1).18^1 .82^10 P(2 broke) =C(11,2).18^2 .82^9

**stats**

p yes broke = .18 p not broke = .82 P(0 broke) = 1*.18^11 * 1 P(1 broke) = C(11,1).18^10 .82^1 P(2 broke) =C(11,2).18^9 .82^2 C(11,1) = 11 C(11,2) = 55

**physics**

Once again you have not given the moment arms Torque or moment is force * distance from axis

**algebra**

(6-4)/(2-3) = 2/-1 = -2