Saturday

October 22, 2016
Total # Posts: 27,510

**math**

.75 * 60 = .3 x x = .75 * 60 / .3 = 150

*March 19, 2016*

**huh?**

I do not understand your notation. What is po3-4 ????

*March 19, 2016*

**Prob/Stats**

p eat = .44 p not eat = .56 p that k say yes (binomial) P(17/k) = C(17,k) .44^k .56(17-k) where C(17,k) = 17!/[k!(17-k)!] do that for k = 8 through 17 and add OR approximate binomial expansion with normal distribution mean = n p = .44 * 17 = 7.48 sigma^2 = 17(.44)(.56) = 4.19...

*March 19, 2016*

**math**

.7 * 225 = 157.50 so no no 70% of original is 30% OFF original

*March 19, 2016*

**mathematics**

Huh Mauricio ????

*March 19, 2016*

**mathematics**

sketch it first length QR = 10 NOTE - perpendicular to x axis so altitude along x axis altitude from P to QR is along x axis and of length 9-3 = 6 so area = (1/2)(6)(10) = 30

*March 19, 2016*

**binomial expansion help!!!**

He said: Actually, just consider the definition of T. Take a peek here, and it should be clear, since the arc length is just ∫ ds = ∫ |dr/dt| dt 88888888888888888888888888 In other words the tangent is along the curve so if you integrate the tangent along the curve...

*March 19, 2016*

**binomial expansion help!!!**

You are welcome.

*March 19, 2016*

**binomial expansion help!!!**

(n+1)n(n-1)(n-2)/24 = 6 k is (n+1)n [(n-1)(n-2) ]= 72 * 2 k BUT [(n-1)(n-2)] = 2 k so (n+1) n = 72

*March 19, 2016*

**binomial expansion help!!!**

(1+x)^(n+1) = 1^(n+1) + (n+1)1^n x + (n-1)(n-2)/2 1^(n-1)x^2 + (n+1)n(n-1)/6 1^(n-2) x^3 +(n+1)n(n-1)(n-2)/24 1^(n-3)x^4 huum (n+1)n(n-1)(n-2)/24 = 6 k (1+x)^(n-1) = 1^(n-1) + (n-1)1^(n-2) x + (n-1)(n-2)1^(n-3)/2 * x^2 so (n-1)(n-2)/2 = k (n-1)(n-2) = 2 k so (n+1)n (2k)/24 = 6...

*March 19, 2016*

**Math**

they have 4/5 2/5 and 2/5 3/5 and 1/5 1/5 and 3/5 or many others like if we say 4/5 = 8/10 or even 16/20 1/10 and 7/10 etc :)

*March 19, 2016*

**math**

3/4 cup / 1/4 tbsp = 3 cups / 1 tbsp

*March 19, 2016*

**Phys 2425**

between wires field is down from one of them and up from the other The B from a wire times 2 pi * distance from the wire is proportional to the current through so 1/2pir = 2/ 2pi(2 -r) 2 r = 2 - r 3 r = 2 r = .66666666667 cm :)

*March 18, 2016*

**Pre algebra**

2 w = L/2 or L = 4 w perimeter = 2(L+w) = 2( 5 w) = 10 w = 10 so w = 1 L = 4

*March 18, 2016*

**Physics**

momentum = m v = .025 * 300 stops in .03 meters average speed during stop = 150 m/s time to stop = .03 meters/150 m/s force = change in momentum/time = .025 * 300 / (.03/150) = 37,500 N do B the same way

*March 18, 2016*

**math**

a + b + c = 408 b = c + 7 so c = b-7 b = a + 5 a + (a+5) + (a+5-7) = 408 3 a + 3 = 408 a + 1 = 136 a = 135

*March 17, 2016*

**mAth**

You are welcome.

*March 17, 2016*

**mAth**

[ (x-2.6)/0.3 ] 3 = -48 (x-2.6)/0.3 = -16 x - 2.6 = -4.8 x = -2.2

*March 17, 2016*

**math**

4/5 * 3/4 * 2/3 = what was left in the end = .4 of original is left at the end call original amount 1 then youngest gets .2 that leaves .8 then middle gets .8/4 = .2 as well that leaves .6 oldest gets .6/3 = .2 ROTFL !!!

*March 16, 2016*

**algebra**

short leg = x long leg = x+8 hypotenuse = 2x-8 so { 2(x-4) }^2 = x^2 + (x+8)^2 4 (x^2 - 8 x + 16)= x^2+x^2+16x+64 4x^2 -32 x + 64 = 2 x^2 +16 x + 64 2 x^2 -48 x = 0 x = 0 works but x = 24 ******************* check 24 , 32 , 40 or /8 3 , 4, 5 LOL yes, right triangle

*March 16, 2016*

**Geometry**

As the problem is stated, of course they will because as it rises the horizontal distance from the pivot point at the ground decreases. If the wires are exactly above the tip of the bean at 60 deg, then they will be closer to the pivot point at more than 60deg Therefore I ...

*March 16, 2016*

**Math**

12 * 20 * 7 * 8

*March 14, 2016*

**physics 11th class**

m g h / t

*March 14, 2016*

**ratios/algebra**

8/5 = 64/x 40

*March 14, 2016*

**Physics**

heat to melt + heat to raise 10 deg = m * heat of fusion + m *specific heat * (10-0)

*March 14, 2016*

**Math**

t = k L/n 6 = k 4/100 so k = 150 t = 150 (16/160) = 15 weeks

*March 11, 2016*

**Chemistry**

only if you know the molar mass of each and the balanced equation so you can see how many moles and therefore grams of A are needed to react with B. So in general, No

*March 11, 2016*

**Math**

it was evidently launched straight up in which case: h(t) = 73.5 + 9.8 t - (1/2)g t^2 g is about 9.81 m/s^2 so h(t) = 73.5 + 9.8 t - 4.9 t^2 at ground, h(t) = 0 so 0 = 4.9 t^2 - 9.8 t - 73.5 and yes you can take 4.9 out approximately 0 = t^2 - 2 t -15 (t-5)(t+3) = 0 t = 5 seconds

*March 11, 2016*

**Algebra**

F = k m g v^2/R (actually k g = 1 because v^2/R is centripetal acceleration) anyway 400 = k (1600) 50^2/800 so k(1600) = 800 * 400 /2500 F = k (1600) 60^2 /600 F = 800*400 *3600 /{2500*600) = (8/6)(36/25)*400 = (4/3)(36)(16) = 768 pounds

*March 11, 2016*

**huh?**

pi r^2 = 3.14 * 64 ft^2

*March 11, 2016*

**Science**

14 agree 15 I suppose but just the word "vital" would do. Depends on what your text says. These questions stink. 16 yes (and that gives away the earlier question :) 17 Heat? Depends on what your particular text says again. 18 yes, evaporates 19 consumer ? 20 yes, ...

*March 11, 2016*

**Science**

8 no idea, check your text for screwy comparison 9 yes d eats plants and fish 10 c yes I suspect 11 I bet on a 12 b I think but minor effect 13 a yes

*March 11, 2016*

**Science**

7 d I think, no light

*March 11, 2016*

**Science**

1 yes 2 no idea what they are getting at. Merry go round correct for physics, not biology 3 c yes 4 yes, came on Mayflower :) 5 c yes 6 c yes

*March 11, 2016*

**maths**

r = 44/2pi = 7 cm area = pi (49) = 154 cm^2 square side = 11 area = 121 cm^2

*March 11, 2016*

**math and science**

v = Vi + a t 0 = 36 + a t t = -36/a d = Vi t + .5 a t^2 40 = 36 (-36/a) + .5 (a)(36^2/a^2) 40 = - 36^2/a + .5 *36^2/a 80 a = -36^2 a = -16.2 m/s^2 then F = m a = -1500(16.2) Newtons

*March 11, 2016*

**Math**

2 x + y = 320 x y = 12,600 so y = 12,600/x 2 x + 12,600/x = 320 x^2 + 6,300 = 160 x x^2 - 160 x + 6,300 = 0 x = [160+/-sqrt(25600-25200)]/2 x = [ 160 +/- 20] /2 x = 90 or 70 try 90 then y = 140 2x + y = 320 Yes, that works try 70 y = 180 2x+ y = 140 + 180 = 320, Yes that works

*March 11, 2016*

**math**

multiply both sides by -1 (-1)(-y) = + y (-1)(3) = -3 so y = -3

*March 11, 2016*

**math**

2 ends are 16*14 2 sides are 4.8*14 top and bottom are 4.8 * 16 so 2(16*14 + 4.8*14 + 4.8*16)

*March 11, 2016*

**math**

13 + 13 = 26 13 hearts and 13 clubs

*March 9, 2016*

**Math**

y = 10 x + 4 (-2, -16) (-1 , -6) (0 , +4} (1 , 14) (2 , 24)

*March 9, 2016*

**Math**

slope = (-6+1)/(1-0) = -5 so y = -5 x + b 9 = 10 + b b = -1 so y = -5 x -1 or 5 x + y = -1

*March 9, 2016*

**PHYSICS ( PERIODIC MOTION)**

if damping proportional to v F = -kx -bv then x = A e^-(bt/2m) sin w' t five cycles is about 3.67 seconds so 1/2 = e^-(3.67 b /.226) take ln both sides -.693 = - -16.2 b so b = .0427 then w' = sqrt (k/m -b^2/4m^2) = sqrt (73. - .035) =8.542 = 2 pi/T T = .7355 s change ...

*March 9, 2016*

**PHYSICS ( PERIODIC MOTION)**

mass = .1136 kg g = 9.81 m/s^2 so weight = .1136*9.81 = 1.114 Newtons spring constant k = 1.114 N/ .134 meters = 8.32 N/m T = 2 pi sqrt(m/k) = 2 pi sqrt (.1136/8.32) = 0.734 s = 7.34 * 10^-1 s

*March 9, 2016*

**Maths**

(1/2)M + (1/3)M + 40 = M multiply by 6 3 M + 2 M + 240 = 6 M 240 = M spent M-40 = 200

*March 9, 2016*

**Science**

In English units, the acceleration of gravity near the surface of earth is about 32 feet/second^2 = g When we used those units, we defined mass in slugs. mass in slugs m = weight in pounds/g = weight in pounds/32 Then we could use Newton's second law F = m a where force is...

*March 9, 2016*

**Math**

one is 16 * 5 the other is (40 - 5) = 35 *5 so 80 *5 [ 16+35 ] = 80*5*51-

*March 9, 2016*

**Physics**

In English units, the acceleration of gravity near the surface of earth is about 32 feet/second^2 = g When we used those units, we defined mass in slugs. mass in slugs m = weight in pounds/g = weight in pounds/32 Then we could use Newton's second law F = m a where force is...

*March 9, 2016*

**english**

verbs like worked SLOWLY or ate quickly An ly at the end is a dead giveaway but is not always the case.

*March 9, 2016*

**Precalculus quadratic stuff**

Lets complete the square to look at the parabola y = -2x^2+16x+40 x^2 - 8 x -20 = -y/2 x^2 - 8 x = -y/2 + 20 x^2 - 8 x + 16 = -y/2 +36 (x-4)^2 = -(1/2)(y-72) so max area occurs when x = 4 and area = 72 zeros are when x^2-8x-20 = 0 (x-10)(x+2) = 0 or when x = 10 and when x = -2...

*March 9, 2016*

**Math**

25 x >/= 5000 x >/= 200

*March 8, 2016*

**Physics HW Plz help**

the fundamental frequency is called the first harmonic Higher harmonics are integer multiples of the fundamental we know 24/3 = 8 1 f = 8 2 f = 16 3 f = 24 4 f = 32 5 f = 40 6 f = 48

*March 8, 2016*

**Algebra**

LOL, yes, just use a square

*March 8, 2016*

**Physics grade 12**

2/x^2 = 8/(12-x)^2 1/x^2 = 4 /(12-x)^2 4 x^2 = 144 - 24 x + x^2 3 x^2 + 24 x - 144 = 0 x^2 + 8 x - 48 = 0 (x+12)(x-4) = 0 x = 4 cm then 12 - x = 8 cm check 2/16 = 8/64 ??? yes right

*March 8, 2016*

**math**

.06 * 300 = 18 empty (answer) .06 * 310 = 18.6 do not show of the 310 310 - 18.6 = 291.4 show up (answer) additionally 300 seats - 291.4 passengers = 8.6 empty seats which is really 18 empty because 40% of a passenger takes a whole seat

*March 8, 2016*

**math**

.98 * 15,000 = 14,700 Only 2 percent will arrive late so your flight will probably be on time. Of course the key word is "probably" and there is no way you can tell if yours is one of the two out of one hundred that are late.

*March 8, 2016*

**No diagram**

If you tried to copy and paste a picture, that does not work.

*March 8, 2016*

**math**

0.06 * 500 = 36

*March 8, 2016*

**history**

http://en.wikipedia.org/wiki/Afro-Asian

*March 8, 2016*

**math**

20 * 8 = 160 player days 0.80 * 160 = 128 player days or an average of 16 players/day

*March 8, 2016*

**phy 231**

x = 1.5 sin (2 pi * .181 t) = 1.5 sin (1.137 t) v = dx/dt = 1.5* 1.137 cos (1.137 t) v max = 1.5 * 1.137 a = d^2x/dt^2 = -1.5*1.137^2 sin (1.137 t) a max = 1.5 * 1.137^2

*March 8, 2016*

**physics**

surface tension is force/length I am going to call density rho, not P. P is confusing because usually pressure. F = m a = rho L^3 * L/s^2 = rho L^4/s^2 so F/L = rho L^3/s^2 but g is L/s^2 so F/L = rho L^2 g if our length scale is h then Y = F/L = constant * rho h^2 g By the ...

*March 7, 2016*

**math help fast**

http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

*March 7, 2016*

**math help fast**

http://www.mathsisfun.com/algebra/sequences-sums-geometric.html

*March 7, 2016*

**math help fast**

2. -4,8,-16,32,... -4 to + 8 is +12 then it goes DOWN 12 so not arithmetic, different d now is it geometric? 8/-4 = -2 -16/8 = -2 32/-16 = -2 = r SO GEOMETRIC next term is 32 * -2 = -64 so the middle one. I do not understand why you are having trouble with these.

*March 7, 2016*

**math help fast**

#1 is Arithmetic with d = 5 It is NOT geometric r = 29/24 = 1.208 r = 19/14 = 1.357 1.208 is NOT 1.357

*March 7, 2016*

**matg**

if in degrees sum of angles in triangle = 180 x - 7 + x + 3 x + 2 = 180 5 x - 5 = 180 5 x = 185 x = 37 x-7 = 30 3x+2 = 113

*March 6, 2016*

**Physics 12**

length on table = x length over side = 2-x mass/meter length = m mass on table = m x max friction force =.5 m g x mass over the side = m(2-x) weight over the side = m g(2-x) if slips when .5 m g x = m g (2-x) x = 2 (2-x) 3 x = 4 x = 4/3 = 1.33 meter = 133 cm

*March 6, 2016*

**physics**

Vi = 36 u = 64 tan A = 36/64 |v| = sqrt (36^2 + 64^2) = 4 sqrt(337)

*March 6, 2016*

**Mathematics grade 9**

regroup to +700 +120 + 3 -200 - 70 - 3 ------------------ +500 + 50 + 0 or 550

*March 6, 2016*

**Networks, Matrices, Linear equations.**

I think the total to X is .2*3000 + .5*2000 + .7*5000 X = |.2 .5 .7 | times the column 3000 2000 5000 so I would write { X Y } column= |.2 .5 .7| |.8 .5 .3| times the column 3000 2000 5000

*March 6, 2016*

**maths**

well their difference is one :) 4 + 5 = 9

*March 6, 2016*

**Physics**

Momentum is conserved period. total kinetic energy conserved? No, where did you get that idea? Think about a bullet hitting a block and getting embedded. I am sure you have done that for homework. You solve it using conservation of momentum. However (1/2)m V^2 of bullet is not...

*March 5, 2016*

**science**

with a simple pendulum period of pendulum = 2 pi sqrt (L/g) ------------------------ with a scale Using a 1 kg weight force down on scale = m g in Newtons, weight = mass in kg * g so g in m/s^2 = weight in newtons / mass in kg Of course your scale is likely to show kilograms ...

*March 5, 2016*

**physics**

If those are at consecutive corners, they cancel each other.

*March 5, 2016*

**Physics**

net force up = 800- m g

*March 5, 2016*

**Algebra**

halfway between 1/2 and 1/10 is (.5 + .1)/2 = .3 = 3/10 not 1/6

*March 5, 2016*

**Algebra**

1/10 = 3/30 1/6 = 5/30 ---------- subtract d = -2/30 = -1/15 check it first two points d = 5/30 - 15/30 = -10/30 = -1/3 This is not an arithmetic progression, typo.

*March 5, 2016*

**trigonometry**

You fly on a "heading" not a "bearing". You take a "bearing", the direction of something, like a lighthouse, from you. Mathematicians are terrible navigators. That said: 60 deg 20' = 60.33 degrees clockwise from North which is 29.67 above +X ...

*March 5, 2016*

**math**

x (x-3) is supposed to be negative if x >3 it is positive if x <0 it is positive it is only positive * negative = negative between 0 and 3

*March 4, 2016*

**math**

Do I get extra credit for finding a harder way ?

*March 4, 2016*

**math**

cos x/sin x + sin x/(1+cos x) = 0 ?? nah, maybe you mean (1+cos x)/sin x + sin x/(1+cos x)=1 (1+cos)(1-cos)/(sin(1-cos)) +sin (1-cos)/[(1+cos)(1-cos)] = 1 (1-cos^2)/(sin-sin cos) + (sin-sin cos)/(1-cos^2) = 1 sin/(1-cos) + (1-cos)/sin = 1 sin^2 + (1-cos)^2 = sin(1-cos) (1-cos^...

*March 4, 2016*

**physics**

It has to get 40 m high when it gets 40 m high, it must have a centripetal acceleration of 1 g or it no longer touches its track. so Ac = v^2/r = 9.81 m/s^2 v^2 = 20*9.81 v = 14 m/s now it has to drop a distance m g h = (1/2) m v^2 to the TOP of the wheel h - 40 = .5 v^2/g but...

*March 4, 2016*

**Physics**

normal force = m g cos 26.8 so friction force = .26 m g cos 26.8 force down slope = m g sin 26.8 so m g sin 26.8 - .26 m g cos 26.8 = m a a = g [ sin 26.8 - .26 cos 26.8]

*March 4, 2016*

**Math**

the area of a cube divided by the volume? 6/s did you use a + where it should have been = ? area of sphere divide by volume ? 3/r area of right circular cylinder divided by volume ? 2/h + 2/r = 2 (r+h)/rh

*March 4, 2016*

**Sorry, all I have time for**

That is all I can try tonight.

*March 3, 2016*

**calculus**

b) Let z = x + iy. Obtain the real and imaginary parts of the function f(z) = 1/(1+z) I assume f(z) = 1/[(1+x) +iy ] = [(1+x)-iy] / {[(1+x) +iy ][[(1+x)-iy] } = [(1+x)-iy] /{(1+x)^2 +y^2} = (1+x)/{(1+x)^2 +y^2} - i y /{(1+x)^2 +y^2}]

*March 3, 2016*

**calculus**

T is theta z = r e^iT = r (cos T + i sin T) z^3 = r^3 e^3iT = -1 if r = 1 e^3 i T = -1 = cos 3T + i sin 3T 3T can be pi or 3 pi or 5 pi so T = pi/3 or pi or 5 pi/3 so z = e^i(pi/3) or e^i(pi) or e^i(5 pi/3) for pi/3 z = cos pi/3 + i sin pi/3 = .5 + .866 i for pi z = -1 (well ...

*March 3, 2016*

**Physics**

angular momentum before =I w=.19 * .0684 + .486(.418)^2*0 = .013 new I w = (.19 +.085)w so .013 = .275 w w = .047 rad/s

*March 3, 2016*

**Weight Is Force! Science**

where it has a mass of 390000 N that is a typo should be where it has a WEIGHT of 390000 N m g = w 9000 g = 390,000 g = 390/9 = 43.3 m/s^2

*March 3, 2016*

**physics**

Ac = v^2/r v increases but there is no radial force so v^2/r has to be the same so r has to increase.

*March 3, 2016*

**No**

I choose 2 2+4 is LESS than 7

*March 3, 2016*

**Math**

y = 3 x y = x^2 y = sin x then relations that are not functions y^2 = x or y = x^(1/2) two values of y for every x y = sin^-1 (x) for every x there is an infinite number of y values like if x = 1/2 y = 30 deg, y = 150 degrees etc x y 1 -1 0 0 1 1

*March 3, 2016*

**Math**

well, 2 a b = 0 so either a = 0 or b = 0 or both :) b ) let me see 5 - 5 = 0 I think true c) I suppose so d) sure n/1

*March 3, 2016*

**Math**

(52 g/85 cm) 10 cm = 6.12 g

*March 3, 2016*

**Math**

find probability that all are green first one 4/9 second one 3/8 third one 2/7 all green = (4/9)(3/8)(2/7) answer = 1 - that result ============================= find probability that 9 of 9 are red find probability that 8 of 9 are red that sum is the probability that zero or ...

*March 3, 2016*

**Physics**

weight = 7 * 9.81 Newtons force down slope = weight * sin 30 = (1/2)weight force up slope = 381 N net force up slope = 381 -(1/2) weight = 347 N a = F/m = 347/7 = 49.5 m/s^2 v = 5 + a t v = 5 + 49.5 t distance = average speed * t 9 = (1/2)(v+5) t 18 = (10+49t) t 49 t^2 + 10 t...

*March 3, 2016*

**physics**

power = work/time since the time is the same, the power ratio is the work ratio work in = kinetic energy out kinetic energy proportional to v^2 [ like (1/2)m v^2 ] v'^2/v^2 = 16

*March 3, 2016*

**math**

1/3 of a pint = 1/3 of 1/2 qt = 1/6 qt or 1/3 of 2 cups = 2/3 cup 1/3 pint * (1 gal/8 pints)(1 barrel/55 gallons = 1/(3*8*55) = 1/1320 barrels :) or whatever

*March 3, 2016*

**PHYSICS HELP**

(a) m g = 9.81 * 4.5 = 44.15 N (b) 44.15 cos 12 (c) 44.15 cos 25 (d) what else is new?

*March 3, 2016*