# Posts by Damon

Total # Posts: 30,063

**maths**

r^2 = 25 +25*3 = 100 so r = 10 tan theta = sqrt3 in quadrant III 60 degrees below x axis pi + pi/3 = 4 pi/3 you are in third quadrant because x and y are negative

**Math**

out = in / 10

**History**

no NO NO ! no Hey, google all four topics!

**Math**

what if y = x^3 ----> y =x^1/3 is function y = x ---> y = x is function 2 y = x^3 + x ---> y+y^3 = 2x y(1+y^2) =2 x for x = 0 y = 0 or y = +/-i more than one value off y for x = 0, no, no for function

**SCIENCE**

I suppose 4, but I would call it habitat re-creation to combat habitat fragmentation.

**Social Studies**

C is certainly true historically but I do not know what period you are talking about. (Russo-Japanese war, World War 2 ??)

**What excerpt ?**

I do not see your excerpt. I would be inclined to agree with all of the above but have not seen what you read.

**SCIENCE**

LOL, that was easy ;)

**Social Studies**

Gee, Google it. I would go back to the original thin Spanish settlement claim to Texas, New Mexico, Arizona, California and parts of other states and the fact that they did not send a lot of settlers thereby letting people from the US settle. Be sure to cover the fact that ...

**Algebra 2**

They mean a,b,c,d by the way + and complex pair -5 +/- 2 i sqrt 5

**Algebra 2**

http://www.wolframalpha.com/widgets/view.jsp?id=3f4366aeb9c157cf9a30c90693eafc55

**Math**

6.8 min / 1 mile 30 min * 1 mile/6.8 min = 4.41 miles

**math**

1. yes 2. yes, works for any old y 3. just like 2 4. yes

**PHYS-041-Keiler: Physical Science**

assuming 5730 year half life a = Ai e^-kt a/Ai = .5 = e^-k(5730) ln .5 = -k(5730) k = 1.21 *10^-4 so a = 22 e^-(1.21*10^-4*11400) = 22 * e^-1.38 = 22* .252 = 5.54 kg

**physics**

T = 2 pi sqrt(L/g)= (2 pi/sqrt g)L^.5 = 1 second at 22 deg so you can get initial L dT/dL = (2 pi/sqrt g).5 /sqrt L dT/dt = dT/dL * dL/dt so what is dL/dt dL/L = 24*10^-6 dT dL /dT = 24*10^-6 L dL/dt = dL/dT *dT/dt = 24*10^-6 (-.625) L so dT/dt = [(2 pi/sqrt g).5 /sqrt L][24*...

**Physics**

assume I = (1/2) m r^2 for disk = (1/2)(6.5)(r)^2 Torque = I alpha where alpha = ang acceleration = a/r T = tension in rope so torque = T * r = I (a/r) T = I a/r^2 = (.5 m )a=.5(6.5)a now the block force down = m g force up = T ma = mg - T T = mg-ma = 2.5(g-a) so putting them ...

**Stoichiometry**

4.5 grams, look below at earlier question

**Math**

12 marbles to start drew one yellow 4/12 then 11 marbles of which 3 are yellow 3/11 so 4/12 * 3/11 = 1/11

**maths**

cost = 1040 - 240 = 800 (240/800)100 = 30% profit 12 * 6.50

**Stoichiometry**

(75/1000).6 = .045 mol CaCO3 = 100 g/mol so 4.5 grams

**Stoichiometry**

CaCl2 + Na2CO3 ---> CaCO3 +2NaCl one to one in mols of each 75 *.6 = x * .4

**maths**

2400 * .15 2400 * 1.15 .8*2400 before VAT

**maths**

0.8 Liters * n = 36 Liters n = 38/0.8 = 45 cans ======================= b makes no sense to me. It is a typo I think.

**Math**

t/5 = (t-5)10 t = (t-5)50 t = 50 t -250 49 t =250 t = 250/49

**Probablility**

I assume you never use the same machine twice first cardio = 4/10 = 2/5 second = 3/9 =1/3 third = 2/8 = 1/4 fourth = 1/7 product = 2/5 *1/3*1/4*1/7 = 1/210 now weight first =6/10 = 3/5 second = 5/9 third = 4/8 = 1/2 fourth = 3/7 product = 3/5 * 5/9 * 1/2 * 3/7 =1/14 so 1/210...

**Algebra**

7-5.375 = 1.625 for left and right margins 1.625 - .3125 = 1.3125 for right margin do the vertical problem the same way

**Algebra**

75*20 + 95*30 = x * 50

**Math**

5 * 3/1 = 15

**pre calculus**

100(-.5 -.866i) - 50 - 50 sqrt3 i

**pre calculus**

we want r(cos T + i sin T) r = sqrt ((-2)^2 +2^2) =sqrt 8 =2 sqrt2 -2 = r cos T = 2 sqrt 2 cos T cos T =-sqrt 2 / 2 T = 3 pi/4 2 = R sin T = 2 sqrt 2 sin T sin T = sqrt2 /2 T = 3 pi/4 all right so z =2 sqrt 2[cos .75 pi+isin .75 pi]

**AP Calculus**

well lets think it might be like a hot stone cooling down to some room temperature Tf Google Newton's law of cooling T = Ts +(To-Ts)e^-(k t) To is your original 1900 time Ts is your final time in 2100 or whatever which is the fastest one can ever go k is a constant that ...

**physics**

Your second method is the right way to go.

**pre calculus**

I think you probably mean: e^(a+bi) =e^a e^bi = e^a (cosb+isinb) then e^i? = e^(0+i?) =(e^0)(cos pi+isinpi) = 1(-1 + 0) or e^i? = -1

**7th grade Pre- Algebra**

R/5 - 6 = -1 add 6 to both sides R/5 +0 = 6 - 1 R/5 = 5 now multiply both sides by 5 (R/5)5 = (5)(5) R = 25

**missing question**

[f(x)-f(a)] /(x-a) = 7 as x-->a is the definition of the derivative f'(a) = 7

**math**

df/dx = 4 x^2/[x^3 +3] at x = -1 df/dx = 4/[2] = 2 so f(-1+dx) = f(-1) + 2 dx here dx = -.1 so f(-1-.1) = -3 +2(-.1) = -3 -.2 =-3.2

**Physics**

t is in seconds 40 t = 42(t-120)

**math**

sin ? = 0 slope = cos ? = -1 f(x) = sin(?) -1(x-?) = -(x-?)

**science**

global positioning systemhttp://www.safewise.com/blog/10-wearable-safety-gps-devices-kids/ ( of course I use GPS to get around the bleak ocean but that is old stuff:) sampling whale snot with drone http://shop.whale.org/pages/snotbot tidal power generation systems http://...

**Electronics**

http://www.electronics-tutorials.ws/rc/rc_1.html

**Math**

s^3 = 512 s = 512^(1/3) calculate s = 8 A = 6 (s^2) = 6 * 64

**Calculus application of sin function**

v = dh/dt = sin pi t then h = - (1/pi)cos pi t but h = A cos (2 pi t/T) so A = -1/pi pi = 2 pi /T so T = 2 so in the ean h =-(1/pi) cos pit = -(1/pi)cos(2 pi t/2) B) h =-(1/pi) cos pit v = dh/dt = sin pi t a = dv/dt = pi cos pi t C)1/pi D) cos 0 = 1 so at t = 0 , 1 , 2 etc E) ...

**second graph link not rights**

http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=8d8e2c27bcaa121d6ee0de4b98774bb4&title=Polar%20Graphs&theme=blue&i0=r%3D2(2-sin^2%C9%B5)^%C2%BD%20&i1=0&i2=Pi%2F2&podSelect=&showAssumptions=1&showWarnings=1

**calculus**

I suspect you mean: r=2(2-sin2?)^½ that makes me nervous that since you do not type exponents you might mean 2-sin^2 ? instead of what your typed. I will assume that first graph it here with sin 2? http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=...

**Science**

mass = 150/g or about 15 kg but who needs it? x = A sin w t v = Aw cos wt a = -Aw^2 sin wt = -w^2 x ============================= when x = .2 = A sin w t v = 5 = Aw cos w t a = +20=+Aw^2 sin w t = +w^2x =============================== so w^2 x = w^2(.2) = 20 w^2 = 200/2 = 100 ...

**Maths**

x^2 y = V G = 4x+y = 6 ================== y = 6-4x x^2 (6-4x) = V now do the complete the square thing like I did in your other problem to find the vertex of the parabola

**Engineering**

4 x = 800 x = 200 feet on a side square ========================= prove that square is max area A = x y P = 2 x + 2 y perimeter so x + y = P/2 A = x (P/2 - x) = -x^2 +P/2 x x^2 - (P/2) x = A find vertex,complete square x^2 - (P/2)x + P^2/16 = -A + P^2/16 (x-P/4)^2 = -(A-P^2/16...

**math**

s = standards d = deluxe 12 s +18 d = 360 ____divide by 6 s + d = 25 ________multiply by 2 2 s + 3 d = 60 2 s + 2 d = 50 -------------- d = 10 then s = 15

**Physics**

assume you mean 5 m/s^2 50 *1000/3600 = 13.9 m/s v = 13.9 - 5 t 0 = 13.9 - 5 t t = 13.9/5 average speed during stop = 13.9/2 d = (13.9/2) (13.9/5) or d = Vi t - .5 (5) t^2 d =13.9(13.9/5)-.5 (5) (13.9^2)/5^2 = .5 *13.9^2/5 the same

**physics**

ub^2 = .25 ua^2 average speed for initial slowing = .5(ua+ub) assume constant a t = .05/.5(ua+ub) = .1/(ua+ub) v = Vi +at ub = ua + a t ub-ua = a (.1)/(ua+ub) .1 a = -(ua^2-ub^2) .1 a = - (.75 ua^2) a = -7.5ua^2 now complete trip 0 = ua + a t t = ua/7.5ua^2 = 1/(7.5ua) d = Vi...

**Math**

There are lots of different ways. perhaps the easiest to understand uses the distributive property 12 = 10 + 2 13 = 10 + 3 (10 + 2) (10 + 3) = 10 (10+3) + 2 (10+3) = 100 + 30 + 20 + 6 = 100 + 50 + 6 = 156 ========================== You can shorten that by saying 10(13) + 2(13...

**Physics**

If there is no moment (torque) then there is no change of angular momentum [ I omega = constant] If they are not opposite in direction through the same point, they cause a moment, called a "couple"

**algebra**

n and 2 n 2 n - n = 20 n = 20 and so answer = 2n = 40

**Gaussian Elimination Method**

LOL, forgot the old easy stuff :)

**Gaussian Elimination Method**

to check, put it back in -4(-1) -(-2) = ? yes 6 12(-1) -2(-2) = ? yes -8

**physics**

m v^2/r horizontal m g down tan theta = mg/(mv^2/R)where theta is angle down from horizontal but cos theta = .7/2.8 so theta = 75.5 deg so tan theta = 3.87 so 3.87 = mg/mv^2/R = 9.81/(v^2/.7) v = 1.33 m/s m v^2/R = .4*1.77/.7 = 1.01 m g = .4*9.81 = 3.92 T^2 = 1.01^2 +3.92^2 T...

**Math**

9*10^-3 LY (5.88*10^12 mi/LY) = 52.92 * 10^9 mi = 5.292 * 10^10 mi

**math!**

q = first questions/min 2 q = final que/min t min for first ten 48 - t min for final 11 q t = 10 so t = 10/q q t + 2q(48-t) = 21 10 + 96q - 20 = 21 96 q = 31 q = 31/96 questions/min so twice that = 62/96 to finish ======================== check t = 960/31 = 30.97 min 48-t = 17...

**Algebra 2**

.75 x + .42 y = .5784 (100) x+y = 100 ============================ .75 x + .42 y = 57.84 .75 x + .75 y = 75 ---------------------- -.33 y = - 17.16 y = 52 x = 48 E

**Physics**

h f = 14.7 eV lambda = c T = c/f c about 3*10^8 m/s

**Physiscs**

well the length is L sqrt 13 but who cares? force up from floor = m g = 3g (because wall is smooth none up there) force sideways from wall = F thus force sideways at floor = F toward wall Now moments about center clockwise mg * 2L/2 = m g L counter clockwise F*1.5 L + F*1.5 L...

**physics**

80 km/hr * 1 hr/3600s * 1000 m/km = 22.2 m/s tan T = v^2/r / g = v^2/gr tan T = 22.2^2/(981) tan T = .502 T = 26 deg 39 min

**Physics**

rho g h 1000 * 9.81 * 20 = 196,200 Pascals = 1.94 atm gage (over 1 atm) or 2.94 atm absolute

**Physics**

done already

**Calculus**

Oh, but I said where x = +/- infinity

**Calculus**

Oh, yes :)O

**Calculus**

Oh my, look around x = 0 and x = 1 and x = infinity and x = -infinity http://www.wolframalpha.com/input/?i=plot+1%2F(x(x-1))

**Math**

a) sin is + in I and II b) cos is - in II so there only c) hard to sketch here from origin up 7 distance 25 x^2 + 7^2 =625 and x is - x^2 = 625 - 49 = 576 x = -24 so point is at (-24,7) cos C = -24/25 tan C = -7/24

**Math**

cos /sin = -1 = cotan 90 + 45 360 - 45

**Consider the linear programming problem**

You are welcome.

**Consider the linear programming problem**

which we could have seen without doing the problem :) The potato seed costs less and the profit is more

**Consider the linear programming problem**

maximize 150 x + 50 y x + y <=70 20 x + 60 y <= 3000 x>= 0 y>= 0 x+y >=1 to fill in input form only http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%20Programming%20Calculator&theme=blue result 10500 at (70,0)

**Calculus**

f' = 10 - 10/x^2 f" = 0 - 10 [ -2/x^3] = 20/x^3 I do not see anyplace where the curvature passes through zero except at x = +/- infinity

**Linear Programming to Maximize Profit**

You are welcome.

**Linear Programming to Maximize Profit**

Oh my heavens I have done so many linear programming problems tonight! s uses 6 plastic d uses 3 plastic so 6 s + 3 d </= 300 s uses 4 metal d uses 8 metal so 4 s + 8 d </= 608 s </=22 maximize 10 s + 2 d I get 332 at (22,56) using http://www.wolframalpha.com/widget/...

**math**

7x = 1.40 x = .20 2x = 0.40 4x = 0.80 5x = 1.00 7x = 1.40 sum = $3.60

**simplex method**

For instructions using Simplex with pivots etc see http://en.wikipedia.org/wiki/Simplex_algorithm

**doing with linear programming**

http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%20Programming%20Calculator&theme=blue max = 3220 at (12,50)

**Calculus**

This is a closed path check first if field is potential in which case integral is zero F = z^2 i + 2xy j + 3y^2k del cross F = 0 ???? nope no way so first line = 3 i + 0 j + 0 k F dot line = Fx *3 = 0*3 = 0 second line in x from 3 to 3 = 0 in y from 0 to 3 = 3 in z from 0 to 1...

**Calc**

or rather curl F

**Calc**

curve is ellipse at z = 11 and 5, y = 0 and x = +/-3 (-3 , 0 , 11) (+3 , 0, 5) at z = 8 , x = 0 and y = +/-3 The normal to that ellipse is in he x z plane and is perpendicular to the line joining(-3, 0 ,11)and (3,0,5) slope of that original line dz/dx = -6/6 = -1 remarkable so...

**MITx**

Just asking :)

**Calc**

You doing an MITx subject?

**Calc**

curl of F over the surface curl is i j k d/dx d/dy d/dz fx fy fz is =(dFz/dy-dFy/dz)i +(dFx/dz-dFz/dx)j +(dFy/dx-dFx/dy)k here Curl F =(ex-9x)i +(y-ey)j +(9z-z)k

**Calc**

Flux = int over S of F dot [1i - (dz/dx)^2j -(dz/dy)^2k] F dot [i -4x^2 j - 4y^2 k] [xy - 4x^2yz -4y^2xz]dx dy now put in 2 -x^2-y^2 for z and do the integrals from 0 to 1

**physics**

if boy at 1 meter girl at (4/3) meter

**physics**

50 N * .2 m = 10 Nm

**The Graphical Method**

I get 40 of A, 0 of B for profit = 1000 maximize 25 x + 15 y constraints 5x+4y<=300 2x+3y<=108 x>=0 y>=0 x+y>=1 (phony to fill fields)

**linear programming**

http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%20Programming%20Calculator&theme=blue try that while I look at your problem

**Algebra 2 (Please help Ms. Sue!)**

292 ?

**Algebra 2 (Please help Ms. Sue!)**

f(x)/(x-a) = f(a) here a = -3 so we need f(-3) f(-3) =(-3)^4-9(-3)^3-5(-3)^2-3(-3)+4 = 81 + 9*27 - 45 +9 + 4 = 81 + 243 - 45 + 9 + 4

**Linear Programming**

note, to make the program format happy I put in max 180x+60y x+y</=60 20x+10y<=700 x>=0 y>=0 x+y>=1 phony but fills boxes

**Linear Programming**

a+b<=60 20 a + 10b </= 700 a and b >=0 maximize 180 a + 60 b intersections at 0,60 35,0 10,50 at a = 0, b = 60 180 (0) + 60 *60 = 3600 at a = 10, b = 50 180(10) + 60(50) = 4800 at a = 35, b = 0 180(35) = 6300 so plant 35 acres of a and zero of b. Use the whole $700 ...

**Linear Programming**

http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%20Programming%20Calculator&theme=blue

**Gaussian Elimination Method**

+5 -4 12 divide by 5 to get 1 -5 +3 +9 +1 -4/5 12/5 multiply by 5 and add -5 +3.0 +9 +1 -4/5 12/5 +0 -1.0 21 multiply by -1 +1 -4/5 12/5 +0 +1.0 -21 so y = -21 now multiply second eqn by 4/5 and add to first +1 -4/5 12/5 +0 +4/5 -84/5 +1 +0 -72/5 +0 +1 -21 x = -72/5, y = -21

**Physics**

sure, if you use a seesaw, you must be twice as far from the pivot point as the weight is. You must move twice as far down as the weight moves up. (draw geometry) You could use a pulley with one end of the line attached to the ceiling, then running down through the block on ...

**Calculus**

depth = h dV/dh = area of surface (draw it :) dV/dh = pi r^2 = surface area r = (2.7/4.3)h remember to use chain rule. for example dV/dt = 59.5 m^3/min but dV/dt = dV/dh dh/dt so dh/dt = 59.5/ (pi r^2) etc

**Science**

Now what American mammal is marsupial?

**Science**

eg: http://www.ucmp.berkeley.edu/mammal/marsupial/marsupial.html

**Science**

google kangaroo, marsupial :)