# Posts by Damon

Total # Posts: 29,823

Math
k x^2 -3k x - 2 = 0 a = k b = -3k c = -2 look at b^2 - 4 a c look at parabola y = 9k^2 + 8 k must be 0 or + for 0 k (9k+8) = 0 k = 0 or k= -8/9 between them, y is negative SO k</= -8/9 or k>/=0

Math
(x+5)/(y+5) = 2/3 (x-5)/(y-5) = 3/7 ------------------ ------------------ 2 y + 10 = 3 x + 15 3 y - 15 = 7 x - 35 ------------------------ ------------------------ 3 x - 2 y = -5 7 x - 3 y = 20 ---------------- ----------------- 9 x - 6 y = -15 14 x -6 y = 40 ----------------...

Maths
r = 55/2pi big area = pi (r+3.5)^2 little area = pi (r)^2 subtract

maths
b^2-4ac says it all in (a) for example 36-4(21) is negative so sqrt of negative in sollution so complex roots (b) 36 + 4(21) is + so real roots (c) x^2 + x/25 = 0 x(x+1/25) = 0 x = 0 or x = -1/25 (d) ?

maths
x = 15/7 y = 4/7 z = -40/7

maths
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx for the first one for example there are three rows and four columns 1 +1 +1 -3 1 -1 -2 13 1 +0 -4 25

physics
That is correct assuming that the ball is sliding, not rolling. If rolling there is a force back on the bottom of the ball to give it angular acceleration but I suspect you have not covered that. Let's just assume that is a net force of 3 N :) In other words the 3 N is the...

Algebra
150 miles /30 miles/gal = 5 gal

I need help, I'm stuck...what is the correct answe
There are 14 students 7 got less than 7.5 and 7 got more than 7.5 so 7.5 is median for mean 2(4)+2(5)+1(6)+2(7)+3(8)+4(10) =102 102/14 = 7.3

American Government
no taxes no army see: http://americanhistory.about.com/od/governmentandpolitics/f/articles_of_confederation_fails.htm

maths
divide 6 by 2 and square it, 9 x^2 - 6 x + 9 -9 (x-3)^2 - 3^2 3(x^2 + 20 x/3) (10/3)^2 = 100/9 3 [ x^2 + 20/3 x + (10/3)^2 - (10/3)^2 ] = 3 [ (x-10/3)^2 - (10/3)^2 ]

physics
gravity force down slope = m(acceleration down slope) m g sin 37.5 =(m v^2/r) cos 37.5 g tan 37.5 = v^2/r v^2 = r g tan 37.5 = 394*9.81 tan 37.5 v = 54.5 m/s

16 + 169 = 185 = x^2 so x = square root of 185 = 185^0.5 = 13.6

Math
11/15 = .73 10/13 = .77 better

Math
legs = 4 p + 2 c = 52 p+c = 22 so p = 22-c 4(22-c) + 2 c = 52 88 - 2 c = 52 2 c = 36 c = 18 then p = 4

Geometry
tan 75 = 80/d d = 21.4 ft between buildings tan 62 = x/21.4 x = 40.3 = height abobe 80 so 120 ft

Physics
a = .09/480 = 9/48000 m/s^2 dv = a dt = (9/48,000) *7d/w*24h/d*3600s/h = 113 m/s we are assuming constant mass. Possibly fuel or even engine components were ejected. This is just the speed change due to the propulsion. Presumably there are also gravitational forces acting even...

Physics
energy stored in spring = (1/2) k x^2 = (1/2)(100)(.04) work done by friction = mu m g *d so 50*.04 = .2 * 1 *9.81* d solve for d

math
If they were 1 by 1 the diagonal would be 400 say n of them along each side diagonal is then n sqrt 2 =400 n = 400/sqrt 2 but n^2 is number of squares so answer = 400^2/2 =200*400 = 80,000 I suspect you mean the diagonal is 80 cm, not 800 by the way

Math
df = 4 dx so if you go from 3 to 2.9 that is dx = -.1 so df = -.4 and 5 - .4 = 4.6 sure enough

or 5 (3*1000 + 3*100 + 3*10 * 3*1) 15*1000 + 15*100 + 15 * 10 + 15*1 1*10,000+5*1000 + 1*1000+5*100 + 1*100+5*10 + 1*10 + 5 10,000 + 6,000 + 600 + 60 + 5 16,665 again I do not know how you are doing this in your class but suspect distributive property in some form.

5( 3000 + 300 + 30 + 3 ) 15,000 + 1,500 + 150 + 15 15,000 + 1,500 + 165 15,000 + 1,665 16,665

Calculus
x = 5 + 20 t y = -75 + 15 t z =distance =sqrt(25+5625) (I bet you meant 7.5 miles but oh well) dx/dt = 20 dy/dt = 15 at t = 0 x = 5 and y = -75 z^2 = x^2 + y^2 2 z dz = 2x dx + 2 y dy so dz = (x dx + y dy)/z and dz/dt = (x dx/dt + ydy/dt)/z = (5*20-75*15)/sqrt(25+56250

Physics need R
angular momentum of disk = (1/2) M R^2 omega final angular momentum of debris initial = m R^2 (v/R) = m v R so m v R = (1/2) M R^2 omega omega = 2 v (m/M) /R

Chemistry (atoms)
1 mole of water H2O has one mol of O so we have .0595 * 6.022*10^23 atoms

MATH
A = x y 50 x + 20 (2y) = 2000 or 5 x + 4 y = 200 5 x + 4 A/x = 200 5 x^2 - 200 x - 4A = 0 where is vertex of parabola? -b/2a = 200/10 =20 so x = 20 5(20) + 4 y = 200 4 y = 100 y = 25

Physics
s = speed 45.9 = u T where u = s cos 40 so T = 45.9 /(s cos 40) where T is time aloft rise time is half T or t = T/2 v = Vi - g t Vi = s sin 40 at top v = 0 s sin 40 = 9.81 t = 9.81[45.9/(2s cos 40] or 2 s^2 sin 40 cos 40 = 9.81*45.9 remember trig now

physics
m a = G m Mmoon /R^2 so 1.62 = G Mmoon/(1.738*10^6)^2

Physics
assume you mean cross product no what if they are perpendicular ?

physics
force = rate of change of momentum which is m a if the mass is constant 10 Newtons = change of momentum/0.10 second so change of momentum = 1 kg m/s by the way the change in speed would be 1/5 = .2 m/s

questions all the same
water density, rho, is about 1,000 kg/m^3 the mass of a column of water one square meter in cross section and h meters high is therefore: mass = rho * 1 * h = 1,000 h kilograms the weight of that mass is mg = 1,000 * 9.81 * h Newtons the pressure is that force over the one ...

hold it
Bob seems to be using vi both for vertical and horizontal speed I think in fact the original vertical speed is zero so h = Hi + 0 -4.9 t^2 1.8 = 21.9 - 4.9 t^2 t^2 = 4.1 t = 2.03 seconds to fall now the car has to go horizontal 58 meters in 2.03 seconds so I will call the ...

solve what for t?
Is it something like sin t = .5 or something?

physics need asap help
initial x momentum = m u initial y momentum = 2 m v final x momentum = 3 m (2) cos 37 final y momentum = 3 m (2) sin 37 so u = 6 cos 37 v = 3 sin 37

physics need help
integral of F(x) dx = a x^2/2 + b x^3/3 at 3 this is 9a/2 + 27b/3 at 1 it is a/2 + b/3 subtract 8a/2 - 26b/3 now put in a and b 40/2 + 52/3 etc

history
d is politically incorrect so you better pick c a is pretty funny as is b

Algebra 2
You can easily check this yourself. First 3 + 6 + 2 = 11 sure enough twice as many peanuts as almonds, yes total cost = 1.5*6 + 3*3 + 1.5*2 = 9 + 9 + 3 = 21 so yes, done

Math
takes time t for pump 1 the big one takes time 3 t for pump 2 so pump 1 does 1/t jobs/hr pump 2 does 1/3t jobs/hr (1/t + 1/3t) = 4/3t jobs/hr together (4/3t jobs/hr)9hr = 1 job 12 hours = t

PHYSICS- PROJECTILE MOTION
Your teacher is really trying to get to you with this separation of constant horizontal speed from increasing vertical speed. 89 * 3.10 centimeters if you really mean cm/s

Pre algbra
-20/30 - 9/30

PHYSICS- PROJECTILE MOTION
a) Trick question - it does not change. u = 1.90 b) v = -9.81 t so |v| = 9.81 (0.410) c) speed = sqrt (u^2+v^2) d) tan (angle down from horizontal) = |v|/u

physics
sqrt(9+4)

Calculus
line is y = -5 x + 3 so slope = -5 = slope of tangent f' = slope = 6 x - 7 where is that -5? 6 x - 7 = -5 6 x = 2 x = 1/3 so y = 3(1/9) -7(1/3) + 4

History
World War One?

Physics
Violet bends more than red the slower wavelength bends more so violet is slower

nobody knows
the other two sides must also have lengths.

Physics
f = sqrt (T/[m/L]) / 2L m = 8000 A L so 170 = sqrt (T/8000A)/4 680 = sqrt (T/8000A) also 1% = .01 = T/ (E A) so T/A = .01 E so 680 = sqrt (.01 E/8000) 462400 = .01 E/8000 E = 3.7 *10^11

physics
20 = (1/2)10 t^2 solve for t = 2 seconds d = 15 t =15*2 = 30 m

physics
The total momentum of the system can not change if there is no external force. Therefore 4

Math Question
parabola, not a line, because y is squared

Math
12 a + 8.5 s = 10,175 a+s = 950 so s = (950-a) 12 a + 8.5(950-a) = 10,175 12 a + 8075 - 8.5 a = 10,175 3.5 a = 2100 a = 600

Math
4x*1 = 4x

math
4x = 50 x = 12.5

Algebra
10x+4

History
How about basic language (Indo European) ?

Engineering
ABS density varies from 1.0 to 1.4 grams/cc you did not give any units except dollars .437 what? grams, pounds, kg , oz ?

Nobody knows
we do not know how much plastic each part takes

Math
21/4 + 41/16 is 84/16 + 41/16 your turn now

math
her speed = v current speed = 3 time up = 18/(v-3) time down = 18/(v+3) so 18[ 1/(v-3) + 1/(v+3) ] = 8 [ 1/(v-3) + 1/(v+3) ] = 4/9 [ v + 3 + v - 3 ] = (4/9)(v^2-9) 18 v = 4 v^2 - 36 2 v^2 - 9 v - 18 = 0 v = 6 for positive v root ----------------------------- check up speed = 3...

Physics
more like 12.7 did you take the square root? I think not :)

Physics
(1/2) v^2 = 9.81 (8.2) v^2 = 16.4*9.81

math
pi r^2 h = 25 so h = 25/(pi r^2) A = 2 pi r^2 + 2 pi r h but we know h(r) A = 2 pi r^2 + 2 pi r * 25/(pi r^2) A = 2 pi r^2 + 50/r r better be >0

math
he has made .4*20 = 8 of 20 he shoots total of 20 + x shots 8 + x = .5(20+x) 8 + x = 10 + .5 x .5 x = 2 x = 4 ==================== check he has now shot 24 and has made 8+4 = 12 sure enough 12/24 = .5

math
fewer dollars per oz or per pound is cheaper per pound of weight gained.

Math
1.5+1.2 = 2.7

Maths
How many do you think? Draw a picture.

maths
there are 2 pi radians in a circle C = 2 pi R so (2.5/2pi)(2 pi R) = 2.5 R = 2.5 * 8 = 20

algrebra
-6x = 2 x = -2/6 = -1/3

Math
1 1/2 = 3/2 (3/2)(42) = 3 (21) = 63

I don't either
I could say 7 + 31 + 6 = 44 low or 8 + 32 + 7 = 47 high but that would be kind of silly and I would be more likely to estimate using nearest whole numbers 8 + 31 + 7 = 46

math
L + w = 250 so L = 250-w L = 50 + w so 250 - w = 50 + w 2 w = 200 w = 100 L = 150

Math
LOL, ok dividing by 3 is the same as multiplying by 1/3 :)

Math
huh?

Math
(9/5)/3 = 3/5

Math
(-11/8)(14/5) = - (11/4)(7/5) = 77/20 = 3 17/20

Math
1.5 + 1.2

8th pre algebra
By the way that is algebra, not pre algebra :)

8th pre algebra
2(10) - 7 = ? sure enough 13 so you are right BUT actually you ADDED 7 to both sides

Trig
2sin 2Tcos2T/[1 + 2 cos^2 2T -1] = sin 2T cos 2T/ [cos 2T cos 2T] = sin 2T/cos 2T = tan 2T = 2 tan T/[1-tan^2T]

math
6.60/[12*710] or 9.18/[24*500] which is less dollars per mL ?

Physics (Mechanics)
m2 going up is + -m1 g + m2 g sin T= (m1+m2)a -2.5(9.8)+9.8m2 sin T=-(2.5+m2).108 -.8(9.8)+9.8m2sinT = (.8+m2)2.888 ---------------------------------- subtract to get rid of 9.8m2 sin T solve result for m2 go back and get m2 sinT and therefore sin T

math (Help)
if it has the square root of a variable in it (y^.5), it is not a straight line

sure do need steve
I can make no sense at all of your problem statement.

Math Functions
6000 + 1000 x

Math Limits
looks good to me

Math
It has y^2 in it. It is therefore a parabola, not a straight line e.

physics
v = Vi - 9.81 t at 1.7 s 19 = Vi - 9.81 (1.7) solve for Vi, launch speed at 5.4 s v = Vi - 9.81(5.4)

algebra
.55 V1 + .80 V2 = .6(50) and V1 + V2 = 50 so V2 = 50 - V1 .55 V1 + .8(50 -V1) = 30 etc

History
This is pretty important. What do you think?

physics
v = Vi - 9.81 t h = Hi + Vi t -4.9 t^2 ==================== 2.2 = 1.5 + 6.4 t - 4.9 t^2 solve quadratic for t then v = 6.4 - 9.81 t

Physics
72 km/hr = 72000/3600 = 20 m/s

Math
(6.4/2)100 = 320 %

math
you mean 2 - 3^2 ??? 2 - 9 = -7

another way to think about it: (3/4) pic / 1 sec = 6 pic/ x sec (3/4) x = 6 x = (4/3)6 x = 8 seconds

6 pictures[1 second/(3/4) picture] = 6 *4/3 = 8 seconds

Geometry
change in x = -15 change in y = -1 distance = sqrt(225+1) = sqrt(226)

typo
I mean .131/16 = .008 mols O

Science (Chemistry) Ratio of mole
If you had used mols O you would have had .13/.16 = .008 or two mols of O for every one of Mg so it would have been MgO2 anyway :)

math
L + w = 42 L + 3 = 4 w 42 - w + 3 = 4 w 5 w = 45 etc

Physics
normal force = m g cos 30 so friction force </= mu m g cos 30 can only say less than if object is not moving. component of weight down slope = m g sin 30 so if no other forces are acting m g sin 30 </= mu m g cos 30 or mu >/= tan 30

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