Sunday

February 1, 2015

February 1, 2015

Total # Posts: 20,453

**Algebra 2**

Intersection of a hyperbola with an ellipse, cool 2 x^2 - 5 y^2 = 1 2 x^2 + 10y^2 = 136 --------------------subtract -15 y^2 = -135 y^2 = 9 so y = +/-3 x^2 = 68-45 = 23 so x = +/-sqrt(23) (sqrt 23 , 3) (sqrt 23 , -3) (-sqrt 23 , 3 ) (-sqrt 23 , -3)
*January 11, 2015*

**math**

The trick is: Out of every four bagels one is sesame and three are plain so that sesame/plain = 1/3 sesame/all = 1/4 = .25 = 25% plain/all = 3/4 = .75 = 75% (1/4) 24 = 6 sesame (3/4) 24 = 18 plain
*January 11, 2015*

**Calculus**

f' = 1/x^2 at x = -3, f = 1/3 at x = -1/2, f = 2 slope = (2 - 1/3)/(-1/2 + 3) = (5/3)/(5/2) = 2/3 where is the derivative = 2/3 ? 1/x^2 = 2/3 x^2 = 3/2 x = +/- sqrt (3/2) yes B
*January 11, 2015*

**Math**

first equation y - x/2 = 5 2 y - x = 10 second equation -x + y/5 = -13 y - 5x = -65 2 y - 10 x = -130 so two equations 2 y - x = 10 2 y - 10 x = -130 --------------------subtract 9 x = 140 x = 15.56 y = 5 + x/2 = 12.78
*January 11, 2015*

**Calculus**

yes, v = 6 t - 3 t^2 dv/dt = 0 at max or min = 6 - 6 t so max or min at t = 1 max or min? d^2v/dt^2 = -6 so max what is that max v at t = 1 v(1) = 6-3 = 3 so C.
*January 11, 2015*

**MATH**

I think you will have to try various interest rates and graph that function if i = .1 or 10% 6.25 = 5.76 if i = .08 6.25 = 6.24 close to 8%
*January 10, 2015*

**Math**

scroll down a bit. I just did that not a good idea to use your real name
*January 10, 2015*

**Polynomials**

it is asking if the left is the same as the right look at a (a-b)(a-b) = a^2 -2ab + b^2 Always then b (a+b)(a+b) = a^2 + 2ab + b^2 NOT a^2+b^2 and is ONLY true if a or b is zero same problem with c You have a typo in d but if that is a + sign then true (a+b)(a+b)=a^2+2ab+b^2
*January 10, 2015*

**Math**

(4x-1)/[(x+3)(x+4)] * (x+4)(x-3)/(2x-1) when you divide fractions, invert the denominator and multiply (x+4) cancels (4x-1)(x-3) /[ (x+3)(2x-1)]
*January 10, 2015*

**Math**

yours (x^2-2x)/(x+1)x (x^2-1)/(x^2+x-6) My work on simplifying the expressions x(x-2)/(x+1) * (x+1)(x-1)/[(x+3)(x-2)] note your sign error in second denominator (x+1) and (x-2) cancel x(x-1) / (x+3)
*January 10, 2015*

**Calculus**

2^1 +2^1 *2^1 + 2^1* 2^2 ..... 2^1*2^(n-1) is 2 + 2*2 + 2 *2^2 .... note 2^1 * 2^(n-1) = 2^n 2^1 =2 = a 2 = r sum from i = 1 to n = 2 ( 1-2^n)/(1-2) = -2 (1-2^n) =2^(n+1) - 2
*January 10, 2015*

**calculus**

Do you mean from 0 to 5 and from 0 to 6 ? if so 2 (x^2 -3 x) at 5 - at 0 = 2 (25 - 15) - 0 = 20 at6 it is 2 (36-18) = 2*18 = 36
*January 10, 2015*

**calculus**

what is the derivative of (5/7)x^7 ? what is the derivative of -x^(-2) ?
*January 10, 2015*

**Physics**

period = T = 60 seconds/26 = 30/13 f = 1/T = 13/30 A = 3.9 cm y = -3.9 cos (2 pi t/T) because y = -3.9 when t = 0 y = - 3.9 cos (26 pi t/30)
*January 10, 2015*

**Math**

I can not simplify it but f(x) = -3(x^2+4x+4) -x-1 = -3 x^3 -12 x -12 - x - 1 = -3x^2 - 13 x -13 sure enough f(x) = [(x-2)(x+1)] / [ (3x+1)(x+1) ] = (x-2)/(3x+1) we win again
*January 10, 2015*

**Math**

(x-2)(x+1)/(x+1) = x-2 = g(x) (x-4)(x+3)/(x+3) = x-4 g(x) = (x-2)(x-4)/(x-2) = x-4 also
*January 10, 2015*

**math**

13,000 = 6,000 +.05(x-20,000)
*January 10, 2015*

**maths**

took me 40 http://www.jiskha.com/display.cgi?id=1420913304
*January 10, 2015*

**maths-6th grade**

sorry I took so long, had a grandson's hockey game in the middle of that.
*January 10, 2015*

**maths-6th grade**

t x 0 0 1 20 2 10 3 30 4 20 5 40 6 30 7 50 8 40 9 60 10 50 11 70 12 60 13 80 14 70 15 90 16 80 17 100 18 90 19 110 20 100 21 120 22 110 23 130 . . . 40 200 averages 5 meters/min
*January 10, 2015*

**maths algebra**

x/2 red x/d blue x - x/2 - x/d = x(1/2 - 1/d) yellow
*January 10, 2015*

**math**

-2 -2*-3 = 6 6*-3 = -18 -18*-3 = 54 54*-3 = -162 etc
*January 9, 2015*

**math**

oh 486 + 440
*January 9, 2015*

**math**

area of cube = 6*49 subtract pi (3.5^2) so cube area painted = 294 - pi(3.5)^2 side area of cylinder = 20 ( 7 pi) end areas = 2 pi(3.5^2) but delete one so total cylinder area =140 pi+pi(3.5^2) total = 294-pi(3.5)^2+140pi+pi(3.5)^2 = 294 + 140 pi = 294 + 20(22) = 294+440 = 734
*January 9, 2015*

**math**

a + 12 d = 159 a + 19 d = 264 --------------- 7 d = 105 d = 15 a = 159-12(15) = -21
*January 9, 2015*

**Math**

[5(x+1) +2(x-1)]/(x^2-1) = -6 5x+5 +2x-2 = -6x^2 + 6 6 x^2 + 7 x - 3 = 0 (2x+3)(3x-1) = 0 x = 1/3 or -3/2
*January 9, 2015*

**Math**

(3x+1)/[2(x+1)(x-1)]+2(x+1)/[2(x-3)(x-1)] [(3x+1)(x-3)+(x+1)^2 ]/[(x^2-1)(x-3)] [ 3x^2-8x-3 +x^2+2x+1 ]/[(x^2-1)(x-3)] [4x^2-6x-2]/[(x^2-1)(x-3)] 2[2x^2-3x-1] / [(x^2-1)(x-3)]
*January 9, 2015*

**math**

along diameter 28/4 + 1 = 8 around semicircle pi D/2 = 14 pi = 14(22/7) = 44 meters or 11 spaces none at ends, already there, so 11-1 = 10 total of 18
*January 9, 2015*

**History**

... and it was Turkey, Greece and Iran in the Middle East by the way. ... and what about Eastern Europe - Poland, Hungary, etc
*January 9, 2015*

**math**

p pencil p - 15 = rulers 3(p-15) = books total = p + p - 15 + 3 p - 45 = 5 p - 60
*January 9, 2015*

**math**

yes 12+3 = 15 :)
*January 9, 2015*

**U.S History**

Google history of US presidential cabinet
*January 9, 2015*

**Science - Please answer as soon as possible**

I would pick b.
*January 9, 2015*

**physics**

weight down = mass times centripetal A down mass cancels, does not matter g = v^2/R
*January 9, 2015*

**incomplete**

You need to know the magnitude of the pulling force. If mass and coef of friction are given and the velocity is constant then it is horizontal force = F cos 30 = m g (mu-sin 30) W = F cos 30 * 20*10^3 J
*January 9, 2015*

**LA - 1 question**

1.
*January 9, 2015*

**Geometry**

A is your statement of the problem B subtract two from both sides C multiply both sides by 6
*January 9, 2015*

**Social Studies help**

If you look at the products on that tree, it looks like we all use coal in one way or another :)
*January 9, 2015*

**Social Studies help**

http://www.coaleducation.org/lessons/twe/bytree.htm
*January 9, 2015*

**Math**

29500 + .041*128500
*January 9, 2015*

**Math**

Yes cos = 0 sin = 1
*January 9, 2015*

**physics**

882 *3.8/9.8
*January 9, 2015*

**Physics and Math**

ball rolls distance 1 + x loss of height = (1+x)sin 30 = .5(1+x) loss of potential energy = 1*9.8*.5(1+x) gain of potential energy = .5 k x^2 = .5 x^2 so 9.8(1+x) = x^2 x^2 - 9.8 x - 9.8 = 0 x = [ 9.8 +/-sqrt(96+39.2)]/2 x = (9.8+/-11.6)/2 x = 10.7
*January 8, 2015*

**Incomplete**

So what is the question ?
*January 8, 2015*

**MNHS_HELP**

I drew 6 8*8 5*5 3*3 2*2 two 1*1
*January 8, 2015*

**English**

I suppose you could say the social context was very lonely, just the nut case and the poor old man. In other words isolated.
*January 7, 2015*

**Physics**

m g sin theta 4 * 9.81 * (1/2) about 19.6 N
*January 7, 2015*

**Science**

Yes, in fact it was Thorium.
*January 7, 2015*

**Science**

it depends on what medium to what medium. Fastest in a vacuum
*January 7, 2015*

**Math**

yes, with some left over.
*January 7, 2015*

**math**

1260 miles (6 gallons/180 miles) = ?
*January 7, 2015*

**Math**

there are more 81 s than anything else
*January 7, 2015*

**Math**

I assume you mean: -x^2/4 + 9 x/5 + 2 = y complete the square first multiply by -4 x^2 - 36 x/5 - 8 = y x^2 - 36 x/5 = y+8 x^2 - 36 x/5 + (18/5)^2 = y + 8 + 12.96 (x-18/5)^2 = y + 20.96 so vertex at ( 3.6 , -20.96)
*January 7, 2015*

**adding and subtracting rational**

(11*8)/(15*8) + (1*15)/(8*15) = 88/120 + 15/120 = 103/120
*January 7, 2015*

**Physics**

infinitely fast, constant acceleration forever m a = m * 9.81 * sin 10.3 so a = g sin 10.3 = 9.81 sin 10.3 so v = (9.81 sin 10.3) t v is proportional to time, forever
*January 7, 2015*

**physics**

(T-30)(10 kg) (heat capacity of water) = 5000
*January 7, 2015*

**physics**

m v^2/r = m g so m cancels of course, has to be the same no matter how many in the car :) v= sqrt (r g)
*January 7, 2015*

**Physical Science HELP**

Zn + I2 ---> ZnI2 the end
*January 7, 2015*

**Math**

I assume x/(x^2-3x-4) - 4/(x+1) ????? x/[(x+1)(x-4)] - 4(x-4)/[(x+1)(x-4)] -3x+4 /[(x+1)(x-4)] blows up if x = -1 or x = 4
*January 7, 2015*

**algebra 2**

(x+4)(x-1) = 0 y = x^2 + 3 x - 4
*January 7, 2015*

**math**

.4 * 50 = 20
*January 7, 2015*

**Math**

x = x^2 + xy + x + y 0 = x^2 + y (x+1) y = -x^2/(x+1)
*January 7, 2015*

**math**

1 1/4 = 5/4 bags 7 1/2 = 15/2 pounds /bag so (5/4) bags *(15/2) pounds/bag = 75/8 = 9 3/8 pounds
*January 7, 2015*

**math**

365.75 km ( 1 hr/133 km) = 2 3/4 hr = 2 hours and 45 minutes
*January 7, 2015*

**Chemistry**

F2O3 ??? 2Fe2O3 + 3C --> 4Fe + 3CO2 ??? maybe mols of Fe2O3 = 3.79*10*24 /6.02*10^23 = 6.30 mols Fe2O3 or 12.6 mols Fe Fe is 56 g/mol so 12.6 * 56 = 706 grams Fe `
*January 7, 2015*

**Math**

sin 24 = h/30 h = 30 sin 24 = 12.2 ft note - do not climb ladder that barely reaches the eaves.
*January 7, 2015*

**Physic**

c = q/v same q on each, call it q so c1 V1 = c2 V2 so V2 = (c1/c2) V1 and V1 + V2 = 1000 V1 + (c1/c2)V1 = 1000 but c1/c2 = 3/6 = .5 so 1.5 V1 = 1000 V1 = 667 V2 = 333 I think you can go back and get q = v c for each
*January 7, 2015*

**Maths**

a + d (n-1) a + d = 7 a + 4 d = 22 ------------ -3 d = -15 d = 5 so a = 2 2 , 7 , 12 , 17 , 22
*January 7, 2015*

**math**

6 / (1/3) = 6 * 3
*January 7, 2015*

**physics**

force = change in momentum/time = (50 kg * 5000 m/s) /s = 250,000 Newtons thrust weight = m g = 60,000*9.81 = 588,600 N no way
*January 7, 2015*

**physics**

m = 30/9.81 a) (30/9.81)v = .005 * 300 b) (730/9.81)v = .005 * 300
*January 7, 2015*

**math**

4.5 in ( 20 mi/in) = 90 miles 90 miles (1 in/18 mi) = 5 inches
*January 6, 2015*

**physics**

(1/2) m v^2 start = m g h at top so m g h = 2 * 10^4 m = 2*10^4 / (9.81*50) = 40.8 kg
*January 6, 2015*

**Science**

Probably with carbon 14 dating. http://dwb4.unl.edu/Chem/CHEM869Z/CHEM869ZLinks/www.all.mq.edu.au/online/edu/egypt/carbdate.htm
*January 6, 2015*

**physics**

5.72*10^3 * 3.11 * 10^3 = 17.8 * 10^6 = 1.78 * 10^7 Joules
*January 6, 2015*

**Math**

30/20 = 1.5 , 90/60 = 1/5 the same 15/20 = 3/4 , 10/15 = 2/3 NOT the same
*January 6, 2015*

**Math**

I would say A
*January 6, 2015*

**Science**

You are welcome
*January 6, 2015*

**Math**

a + d(n-1) a + d (2) = 1985 a + d(7) = 2015 ----------------subtract 0 - 5 d = - 30 d = 6 a + 12 = 1985 a = 1973 1973 + 6(14) = 2057
*January 6, 2015*

**physics**

normal force down = 18.4*9.8 - 126 sin 34.1 so friction force = .123 (18.4*9.8-126 sin 34.1) work done by friction - friction force * 20 meters
*January 6, 2015*

**Science**

Yes That is all per molecule.
*January 6, 2015*

**4th grd math**

3*8 = 24 fish per day 2.5 * 8 = 16 + 4 = 20 eaten so 4 left over each day I guess you do not have seagulls where you live :)
*January 6, 2015*

**Math**

15 sandwiches /.75 hr * 3 hr = 60 sandwiches
*January 6, 2015*

**Science**

You are welcome.
*January 6, 2015*

**Science**

I mean (6/18)*10^23 atoms/gram
*January 6, 2015*

**Science**

2 hydrogens, one oxygen in a molecule so three atoms per molecule a mol is 6*10^23 molecules so 18 * 10^23 atoms per molecule a mol weighs 2+16 = 18 grams so (6/18) * 10^23 molecules per gram
*January 6, 2015*

**math**

sorry, yes
*January 6, 2015*

**math**

39 - 15 = 25 spaces so 25,000 feet 10:11- 10:05 = 6 minutes 25,000/6 = 4167 feet/min a little less than a mile a minute or 60 miles per hour
*January 6, 2015*

**math**

1/4 inch to the foot so one inch = 4 feet 6*4 = 24 feet
*January 6, 2015*

**math**

14/10 = 1.4 lions per tiger or 14/24 = 7/12 lions (not loins I assume) and 10/24 = 5/12 tigers
*January 6, 2015*

**algebra**

there will be a short time on the way up to 28 and a long one for the way down, we want the second minus the first when will h = 28 feet? 28 = 4 + 56 t -16 t^2 16 t^2 - 56 t + 24 = 0 2 t^2 - 7 t + 3 = 0 (2t-1)(t-3) = 0 t = .5 or t = 3 so t = 2.5 seconds above 28
*January 6, 2015*

**Math**

dollars / t shirts = dollars per t shirt A 40/16 = 2.50 per shirt B 140/84 = 1.67 per shirt
*January 6, 2015*

**Math**

You are welcome.
*January 6, 2015*

**Math**

7 d - 4 d - 32 = -8 3 d = 24 d = 8
*January 6, 2015*

**math**

oh, I assumed that the 23 was a typo and it meant 2/3
*January 6, 2015*

**math**

I think you added 6 girls and get 20 out of 30
*January 6, 2015*

**math**

Rodger is right
*January 6, 2015*

**math**

3/7 7+10+7 = 24 total students 14 are girls so 14/24 = 7/12 suspect you mean 2/3 are girls (14+x) /(24+x) = 2/3 42 + 3 x = 48 + 2x x = 6 more girls
*January 6, 2015*

**Math**

" it is also perpendicular line" should be it is at the intersection of two perpendicular lines.
*January 6, 2015*

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