Friday

November 27, 2015
Total # Posts: 22,925

**binomial coefficient**

https://en.wikipedia.org/wiki/Binomial_coefficient
*November 20, 2015*

**College pre calc**

OIC to calculate nCr use nCr = n! / [ r! (n-r)! ] unless you have Pascal's triangle or a binomial coefficient table in front of you Google binomial coefficient i! = i * (i-1) * (i-2)..... 1 when you have a division like 19!/8! you write 10! as 10 * 9 * 8! so you can cancel...
*November 20, 2015*

**College pre calc**

10C8 = 10!/ [ 8! (10-8)! ] = [ 10 * 9 ] * 8! / [ 8! * 2! ] = 90/2 = 45
*November 20, 2015*

**Physics**

The question is meaningless ignoring gravity. In fact it is hard to say ignoring air drag as well. Because the body would presumably reach constant terminal velocity where air drag up exactly balances gravitational force down.
*November 20, 2015*

**Math**

(2x+11y) (w) = 8 x + 44 y w = (8 x + 44 y) / (2 x + 11 y) = 4 (2 x + 11 y) / (2 x + 11 y) = 4
*November 20, 2015*

**Math 1350**

x/7 = A 6/7 = (7 A + 6)/7 x/6 = B 5/6 = (6 B + 5)/6 so x = 7 A + 6 and x= 6 B + 5 7 A +6 = 6 B + 5 6 B - 7 A = 1 what multiples of 7 and 6 differe by one? 35 and 36 or 48 and 49 ? try 35 and 36 A = 5 and B = 6 x = 6 B + 5 = 41 or x = 7 A + 6 = 41 sure enough
*November 20, 2015*

**Math 1350**

12 = 2*2*3 18 = 2*3*3 lowest common multiple = 2*2*3*3 = 4*9 = 36 11/12 = 33/36 1/18 = 2/36 so 35/36 is used and 1/36 remains open fields
*November 20, 2015*

**Algebra 2**

Maybe a rectangle? 2L + 2 W =400 so L + w = 200 so L =200-w L w = 9100 (200-w) w = 9100 w^2 -200 w + 9100 = 0 w = [ 200 +/- sqrt (40000 - 36400)] / 2 w = [ 200 +/- 60 ] / 2 w = 130 or 70
*November 20, 2015*

**Physics**

Hey, I showed you how to do it. Mow use what I showed you.
*November 20, 2015*

**Physics**

Volume = pi R^2 L so mass = rho L pi R^2 rho = density = 1000 kg/m^3 * SG because density of water is 1000 kg/m^3 so mass = 1000 SG L pi R^2 if mass and R are the same then L * SG= maas /(1000 pi R^2) = constant so Ln * SGn = L1 * SG1
*November 20, 2015*

**Algebra**

(4/3)^2 = 16/9 which is less than 2 -70/110 vs -63/100 have to actually do it :( -.636 is less than -.630 (to the left of it on number line) -22/25 versus -80/100 is -88/100 is less than -80/100
*November 20, 2015*

**science**

Hmm, better look at globe - I think A
*November 20, 2015*

**Physics**

Energy stored = (1/2) I omega^2
*November 20, 2015*

**Physics**

then u , the horizontal component = sqrt (final speed^2 - Vf^2)
*November 19, 2015*

**Physics**

If you need components you need to do the vertical problem. It fell from 8 meters up Call vertical component at ground Vf fall from 8 meters (1/2) m Vf^2 = m g (8) Vf = sqrt (16 g)
*November 19, 2015*

**Physics**

I did both horizontal and vertical components Bob (not really needed of course)
*November 19, 2015*

**Do it Bob's way :)**

The way Bob Pursley did it is much easier. You do not need components at all, just kinetic energy gained by falling 2 meters total.
*November 19, 2015*

**Physics**

If you want to do that first part with energy we do NOT know Vi BUT we do know that the thing goes up 8-2 = 6 meters before gravity stops it Vi = sqrt (2 g * 6 meters)
*November 19, 2015*

**Physics**

I gave you components you have vertical component at ground = Vf and find horizontal component the way I did Watch out Bob, 15 m/s is not the vertical component but the total speed
*November 19, 2015*

**Physics**

Now you need horizontal speed. That is easy You have Vi = 10.8 and Vi^2 + u^2 = 15^2 so u = sqrt (225 - 117) and then finally speed out of cannon = sqrt (Vi^ + u^2)
*November 19, 2015*

**Physics**

Now do the second half of the vertical problem I did not notice you said use energy so I will now Call vertical component at ground Vf fall from 8 meters (1/2) m Vf^2 = m g (8) Vf = sqrt (16 g)
*November 19, 2015*

**Physics**

The mass is only included in the problem statement to confuse the student. First do the vertical problem. It had initial vertical velocity component Vi and height 2 meters It went up to 8 meters and then stopped and fell. How long to rise from 2 m to 8 m? v = Vi - 9.81 t at ...
*November 19, 2015*

**math**

9/15 = 3/5 divide top and bottom by 3 3/10 = 3/10 prime number in numerator, no luck 6/10 = 3/5 divide top and bottom by 2
*November 19, 2015*

**Physics**

I omega = constant angular momentum I/2 (2 omega) = I omega twice 4 = 8 radians/second
*November 19, 2015*

**Math**

12 miles/3 hours = 4 miles/hour
*November 19, 2015*

**math**

12 - 1 = 11
*November 19, 2015*

**school math 3rd grader**

Meg went into the store with $8.64 in her pocket She spent $4.89 on toys. How much did she have left to buy candy?
*November 18, 2015*

**school math 3rd grader**

Decimals in Grade 3 addition? 3.75 4.89 -------- 8.64 or perhaps regrouping it into powers of ten 3*1 + 7*.1 + 5*.01 4*1 + 8*.1 + 9*.01 --------------------- 7*1 + 15*.1 + 14 * .01 which is 7*1 + 16*.1 + 4 *.01 which is 8*1 + 6*.1 + 4*.01 which is 8.64
*November 18, 2015*

**Fluid mechanics, Hydraulics**

The area does not determine the pressure but only the force when the pressure is known. All that matters here is the difference in altitude. B is high A is low density * g * 1.75 meters .8 * 1000 kg/meter^2 * 9.81 * 1.75 = 13,734 Newtons/m^2 or Pascals one atmosphere is about ...
*November 18, 2015*

**physics**

I do not care how far it went to the fielder. I am only interested in the vertical problem. it spent 5.5/2 seconds rising v = Vi - g t at top, v = 0 0 = Vi - 9.8 (5.5/2) so Vi = 27 m/s so if you throw up at 27 m/s, how high? two ways: energy: (1/2) m Vi^2 = m g h so h = Vi^2/(...
*November 18, 2015*

**algebra**

2.5 - 3.5 x = 8 - 4 x - 6 4 x - 3.5 x = 8 - 6 - 2.5 .5 x = -.5 x = -1
*November 18, 2015*

**Math (Damon Please help)**

You are welcome.
*November 18, 2015*

**Math (Damon Please help)**

Yes !!!! of course 8 = 2*2*2 but that does not matter right now
*November 18, 2015*

**Mathematics**

oh, you changed a number 2 (1 -sin^2) + 4 sin - 3 = 0 2 - 2 sin^2 + 4 sin - 3 = 0 -2 sin^2 + 4 sin - 1 = 0 2 sin^2 - 4 sin + 1 = 0 (2 sin -1)(2 sin-1) = 0 sin = 1/2 angle = 30 or 150 degrees
*November 18, 2015*

**Solved earlier link**

http://www.jiskha.com/display.cgi?id=1447870446
*November 18, 2015*

**Mathematics**

I already did this today 180-30 360 - 30 270 in degrees multiply degrees by pi/180 to get radians if that is what you need
*November 18, 2015*

**Math**

Juan 1 job/32.35 minutes R 1 job/21.78 minutes L 1 job/23.18 min all three work for t minutes so (1/32.35 + 1/21.78 + 1/23.18) t = 1 job ( .119966 ) t = 1 so t = 8.34 minutes
*November 18, 2015*

**SS plz help me plzzzzzzz**

The paragraph headings are blue when I click on it too :)
*November 18, 2015*

**Math**

(1/4)^2 + 2 ? I am sure you can do that !
*November 18, 2015*

**Physics**

Kinetic energy = (1/2) m v^2 = (1/2)(4)(4) = 8 joules so you need 8 Joules to stop it F = m a 5 = 4 a a = 5/4 m/s^2 = 1.25 m/s^2 5 x = 8 x = 8/5 = 1.6 meter
*November 18, 2015*

**Physics**

m = .00417 kg distance = .0464 meter F * distance = work F = (1/2) m v^2 / .0464 b) easy way is if acceleration is constant then average speed = (initial + final)/2 so average speed = 506.1/2 distance = .0464 so time = .0464/253 = 1.83*10^-4 seconds = 0.000183 seconds
*November 18, 2015*

**Physics**

work done by puller person = F * 28 work done lifting weight = .47 * F * 28 = 13.16 F so 13.16 F = 47 * 9.81 * 7
*November 18, 2015*

**math**

When you get to Chemistry, remember how we did that
*November 18, 2015*

**did something**

12 for 8.40 8.40/12 = 0.7 Rs/egg 0.7 * 1.15 = .805 Rs/egg times 100 = 80.5
*November 18, 2015*

**physics**

Ke = (1/2) m v^2 = (1/2)(.020)(354)^2 = F * d = 0.45 F
*November 18, 2015*

**Physics**

distance up = 2.26 sin 25.6 work = m g h = 7159 * 2.26 sin 25.6
*November 18, 2015*

**physics**

Two are easy :) Force down = m g, does no work, no motion up or down Force up from floor = m g, also does no work The third is easy too work done by input force = +185 * 7.5 = + 1388 Joules Now the negative one, the friction force which is opposite to motion F = - mu m g = - ....
*November 18, 2015*

**Mathematics**

oh, forgot quadrant 4 360 - 30 = 330 degrees
*November 18, 2015*

**Mathematics**

2 cos^2 x - 3 sin x - 3 = 0 but cos^2 x = 1 - sin^2 x so 2 (1 -sin^2 x) - 3 sin 3 - 3 = 0 2 - 2 sin^2 x - 3 sin x - 3 = 0 2 sin^2 x + 3 sin x + 1 = 0 (2 sin x + 1)(sin x + 1) = 0 sin x = -1/2 or sin x = -1 x = 210 degrees or x = 270 degrees now do the second half :)
*November 18, 2015*

**Math NEED HELP NOW! SO CONFUSED! :'(**

3 would be 3 x^2 3) 3x^2y, 9x^2 3 * x * x * y and 3 * 3 * x * x 3*x*x is common to both
*November 18, 2015*

**Math NEED HELP NOW! SO CONFUSED! :'(**

5. 3 * c * d * d * d *d 4 * 3 * c * c * c * d 2 * 3 * c * c * d * d they all have 3 they all have c they all have d so 3 c d
*November 18, 2015*

**Math NEED HELP NOW! SO CONFUSED! :'(**

Now you try
*November 18, 2015*

**Math NEED HELP NOW! SO CONFUSED! :'(**

17 is a prime number. You can do nothing here
*November 18, 2015*

**Math NEED HELP NOW! SO CONFUSED! :'(**

http://www.jiskha.com/display.cgi?id=1447869016
*November 18, 2015*

**Pre-Algebra(please help ASAP!!!!!)**

greatest common factor? well, let's factor them for fun 36 = 6*6 = 2*2*3*3 81 = 9*9 = 3*3*3*3 27 = 3*3*3 well the biggest thing common to all of them is 3*3 which is 9
*November 18, 2015*

**Geometry**

around the outside turn right 6 times 360/6 = 60 so inside is 180-60 = 120
*November 18, 2015*

**Algebra**

18 </= T </= 28
*November 18, 2015*

**I see no attempt to checkH**

Maybe you just want me to try to do it? I already know how.
*November 18, 2015*

**8th grade Pre Algebra**

you need 3 ns and 4 ts n^3 t^4
*November 18, 2015*

**Algebra 2**

y^2 = 16 - x^2 y = +/- sqrt(16-x^2) There must be one and ONLY ONE value of y for every value of x However we have TWO So you are right, y is not a function of x In fact this is a circle with center at the origin and radius 4 The domain is x = -4 to x = +4 The range is y = -4 ...
*November 18, 2015*

**Physics**

all you need to know is the speed of a hunk of water headed up. Q = flow rate = hose area * v Q = pi (.0159)^2 /4 * 2.4 Q = .000477 m^3/second but Q = flow rate = nozzle area * speed Vi = initial speed up .000477 m/s = pi r^2 Vi .000477 = pi (.0064)^2 Vi Vi = 3.7 m/s Now we ...
*November 18, 2015*

**directions**

east 80 + 100 + 120 = 300 north 20 + 60 = 80 sqrt (300^2 + 80^2) = 310
*November 18, 2015*

**math**

1 3/4 = 4/4 + 3/4 = 7/4 3 * 7/4 = 21/4 = 5 1/4 or maybe 1 3/4 = (2 - 1/4) 3 ( 2 - 1/4) = 6 - 3/4 which is 5 1/4
*November 17, 2015*

**Science**

The one with the two metals on the right :)
*November 17, 2015*

**math**

http://davidmlane.com/hyperstat/z_table.html
*November 17, 2015*

**Pre-Algebra**

No You multiply both sides by 4.9 a/4.9 = 8.33 (a/4.9) * (4.9) = 8.33 * 4.9 a = 8.33 * 4.9
*November 17, 2015*

**Math**

shadow/height = constant at this time of day 10/6 = 150/x
*November 17, 2015*

**Maths**

I would be inclined to do it in meters though r = 0.1 meter
*November 17, 2015*

**Calculus**

Thanks, hope so :)
*November 17, 2015*

**Calculus**

w = (5 x^2 + y^2 - 4 z^2)^.5 dw/dx = (5 x)/(5 x^2 + y^2 - 4 z^2)^.5 dw/dy = y/(5 x^2 + y^2 - 4 z^2)^.5 dw/dz = -4/(5 x^2 + y^2 - 4 z^2)^.5 now just plug in 2, -4, 6
*November 17, 2015*

**Calculus**

do this just like the one above for example df/dx = 3 x^2 + 2 y^3 df/dy = 6 x y^2 - 9 d/dx (df/dx) = 6 x etc
*November 17, 2015*

**Polynomial**

I will do one, then you try x (x^2 - 3 x - 4) = 0 x (x-4)(x+1) = 0 so x = 0 , 4 , -1
*November 17, 2015*

**physics**

Lift == k v^2 Lift at 250 km/h = 400,000 g 100 * 140 = 14,000 kg so lift needed = (400,000 -14,000) g Newtons = 386 g Newtons 250^2/400,000 g = v^2 / 386,000 g v^2 = 250^2 (386/400) v = 250 sqrt (.965) v = 245.6 km/h
*November 17, 2015*

**math**

change in y /change in x = 5 y = 5 x + 3
*November 16, 2015*

**Algebra**

sue = s Jill = 3 s Jane = (1/4) s so s + 3 s + s/4 = 36 4 s + s/4 = 36 16 s + s = 144 17 s = 144 s = 144/17 Jill = 3 s = 432/17 Jane = s/4 = 36/17
*November 16, 2015*

**Social Studies**

General P.G.T. Beauregard attacked Fort Sumter. I suspect he gets the credit.
*November 16, 2015*

**Quick English check- ms sue**

I think: 4 is replicate 10 is contend
*November 16, 2015*

**algebra**

There is no unique answer. You have defined a straight line. y = (3/4) x - 10/4 slope is .25 hits y axis at -2.5
*November 16, 2015*

**Geography**

There are so many :(
*November 16, 2015*

**Geography**

Well, that term was used to describe people who fled Vietnam by boat after the war there. However it could apply to people who fled Cuba or fled Syria or fled ........
*November 16, 2015*

**Math**

red + brown = 24 total = 24+18 = 42 so 24/42
*November 16, 2015*

**Math**

9 * 2 = 27 BUT 5 * 5 = 25 !!!!! but still not enough :)
*November 16, 2015*

**math**

L^2 10.5^2 = 110.25 in^2
*November 16, 2015*

**PHYSICS**

5.7 * 1025 = 5842.5 kg of water displaced by ice submerged mass of ice = 5.7 * 917 = 5226.9 kg mass additional to submerge = 5842.5-5226.0 = 615.6 kg mass of maximum bear then weight in Newtons = 615.6 *9.81 N
*November 16, 2015*

**Calculus**

wait a minute that ignored the up parts 32 + 16 + 16 + 8 + 8 + 4 + 4 ..... 32 + 2 ( 16)/.5 = 32 + 64 = 96
*November 16, 2015*

**Calculus**

infinite geometric series a1 = 32 r = .5 sum = a1 (1 - r^n) / (1-r) = 32 (1 - .5^oo) /(1 - .5) =32 /.5 = 64
*November 16, 2015*

**Physics**

The real question is how long does it take anything to fall to the floor from a 2.1 meter table h = (1/2) g t^2 2.1 = 4.9 t^2 solve for t then 16 = u * t
*November 16, 2015*

**PHYSICS**

R1^2/R2^2 = 2180/73.6 so sqrt (2180/73.6)
*November 16, 2015*

**Physics**

1/4 mile = 402 meters average speed = (final speed + original speed)/2 if acceleration is constant v = 140.3/2 = 70.15 m/s time = distance/speed = 402/70.15 = 5.73 seconds check v end = 0 + 30.4 (5.73)? 174 not really ============================ car 1 a = 10/10 = 1 car 2 a...
*November 16, 2015*

**Physics**

v = a t = 33 (.12)
*November 16, 2015*

**please proof read**

figured to be what ? Are you trying to copy and paste? That does not work here.
*November 16, 2015*

**mysterious **

given by what? Presumably some parabola.
*November 16, 2015*

**Algebra**

Straight up I hope. well if so, I happen to have a hunch that the function is h = Vi t - 16 t^2 and the velocity is given by v = Vi - 32 t at the top v = 0 so at top, t = Vi/32 = 96/32 = 3 seconds then h = 96 * 3 - 16 (9) = 144
*November 16, 2015*

**Social Studies**

You are welcome.
*November 16, 2015*

**Social Studies**

Hmmmm ....... Sort of, but it is a tough argument to make. Perhaps because the cotton gin made a vast spread of cotton plantations possible and therefore made slavery a bigger factor in the economy of the United States than it would have been otherwise, it was a contributing ...
*November 16, 2015*

**physics**

.03*600 = ? Newtons
*November 16, 2015*

**Chemistry**

Hmm, well try to write a balanced equation C2 H4 + 3O2 ---> 2CO2 + 2H2O seems ok so for every mol of C2H4 I get 2 mol water C2H4 = 2*12 + 4*1 = 28 grams/mol so 2 grams is 2/28 = 1/14 of a mol so I get 1/7 mol of water water is 16+2 = 18 grams/mol 18/7 = 2.57 grams of water
*November 16, 2015*

**Social Studies**

You "think" that New Mexico has many Hispanics? OR You know perfectly well and it is well documented that New Mexico has many Hispanic residents? If someone "thinks" it, then it is opinion. if it is simply true and documented, then it is a "fact" ...
*November 16, 2015*

**math**

60 + 180 = 140 km journey length time at x = 60/x time at y = 180/y total time = 60/x + 180/y = 10 now interchange total time = 180/x + 60/y = 8 2/3 = 26/3 two equations 60 y + 180 x = 10 x y 180 y + 60 x = 26 x y /3 multiply bottom equation by 3 60 y + 180 x = 10 x y and 540y...
*November 16, 2015*

**Science**

I agree with those I know. I do not know if this one is right or not. My guess would be that you are correct.: Earth's oceans, atmosphere, and continents began to form during the first several hundred years of Precambrian time. A. True* B. False
*November 16, 2015*