Friday

September 19, 2014

September 19, 2014

Total # Posts: 18,540

**science help !!**

I am not sure. Although it is a new technology here and CA will have the first one in the uSA it is hardly groundbreaking in Japan for example. Money, legal challenges, mountains, obtaining rights of way...... http://www.sfbg.com/politics/2014/03/07/california-high-speed-rail-...
*May 21, 2014*

**Science Check Answer?**

You are welcome.
*May 21, 2014*

**Science Check Answer?**

https://www.google.com/search?q=larynx,+trachea,+bronchi,+pharynx,+alveoli&client=firefox-a&hs=wBE&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=fQJ9U9WkHcKLqAaC-ICgCw&ved=0CE0QsAQ&biw=1011&bih=620
*May 21, 2014*

**Math 6 gemoetery**

You are welcome :)
*May 21, 2014*

**Math 6 gemoetery**

LOL, well there is one sure way to find out 93 * 58 * 2.47 = 13,323.18 now 6000*1.5 = 9,000 6000*2 = 12,000 the last two are even lower
*May 21, 2014*

**science**

Yes
*May 21, 2014*

**science**

http://www.thefreedictionary.com/Selectively+permeable
*May 21, 2014*

**science**

you are selecting, which means choosing some and not others to let through
*May 21, 2014*

**science**

Oh come on, make a guess :)
*May 21, 2014*

**Algebra**

13-2 = 11 9-4 = 5 so 11 a + 5 b
*May 21, 2014*

**Science 1 question**

Yes, confusing.
*May 21, 2014*

**Science 1 question**

Yes, A
*May 21, 2014*

**Chemistry**

1 atm is about 1.013*10^5 Pa or 101.3 kPa 101.3 - 2.5 = 98.8
*May 21, 2014*

**Science Check Answers?**

alveolus has high surface area to allow lots of gas exchange
*May 21, 2014*

**English**

B I think yes C yes B
*May 21, 2014*

**Algebra 2**

x = 2 y = -1 sketch graph in Quadrant 4 if theta is angle below x axis sin theta = -1/2 csc theta = 1/sin theta = -2/1
*May 21, 2014*

**math**

x </= 5-2.25 x </= 2.75
*May 21, 2014*

**algebra**

y = 4 x + 1 y + 2 x = 13 so 4 x + 1 + 2 x = 13 6 x = 12 x = 2 then y = 4(2) + 1 = 9
*May 21, 2014*

**Algbera**

add or subtract a full circle (or several of them) 130 + 360 = 490 of course 130 is coterminal with 130 but hardly counts as an answer
*May 21, 2014*

**math**

sure enough, 20 months
*May 21, 2014*

**math**

total paid = 35 * number of months 700 = 35 * n so n = 700/35
*May 21, 2014*

**math**

t is the same for both I assume 65 t + 35 t = distance between LA and NYC t = distance/100 so distance from NYC = 35 * (distance between)/100
*May 21, 2014*

**Calculus**

Oh, if you mean the algebra look at the numerator [ x -(x+h)] = x - x - h = -h
*May 21, 2014*

**Calculus**

h is a small increase in x which is allowed to approach zero to get the slope of f(x) at x, the definition of the derivative Definition of deriviative of f(x) is: df/dx = {f(x+h) - f(x) ]/h as h-->0
*May 21, 2014*

**Calculus**

What do you want, the derivative? if so f(x) = 1/x f(x+h) = 1/(x+h) f(x+h)-f(x) = 1/(x+h) - 1/x = [ x -(x+h)] /[x(x+h)] = -h/ (x^2 + x h) [f(x+h)-f(x)]/h = -1/(x^2+xh) limit as h-->0 = -1/x^2 which is of course the derivative
*May 21, 2014*

**Algebra/Permutation**

in general for n items taken r at a time P(n,r) = n!/ (n-r)! for n = 4 and r at a time P(4,r) = 4!/(4-r)! so for 4 taken 1 at a time 4!/3! = 4*3*2*1/(3*2*1) = 4 or for 4 taken 2 at a time 4!/(2)! = 4*3 *2*1/2*1 = 12
*May 21, 2014*

**Algebra**

whoops, sorry, thanks !
*May 20, 2014*

**Algebra**

mean is 6 yes I get sqrt 80 = 8.94 for SD 2^2 + 2^2+1^2+6^2+3^2+3^2+1^2+4^2 4+4+1+36+9+9+1+16 = 80 sqrt 80 = 8.94
*May 20, 2014*

**Algebra**

That standard deviation is much too big. Are you sure it is not the variance and you forgot to take the square root?
*May 20, 2014*

**geometry**

You are welcome, good luck !
*May 20, 2014*

**geometry**

look at http://www.regentsprep.org/Regents/math/algtrig/ATT1/trigsix.htm you only really need sin, cos, tan for now.
*May 20, 2014*

**geometry**

ok, recipe for right triangle where hypotenuse is opposite right angle: sin of angle = opposite side/hypotenuse cos of angle = adjacent side / hypotenuse tan of angle = opposite side/adjacent side
*May 20, 2014*

**geometry**

Now Taylor, I told you to draw a picture. what is adjacent side, what is opposite side, what is hypotenuse?
*May 20, 2014*

**Physics**

100 sqrt (6^2+1^2) = 100 sqrt 37 = 608
*May 20, 2014*

**physics**

P V = n R T P same n same R same so V = k T V1/T1 = V2/T2 V2 = (T2/T1) V1 V2 = (225/300) (3)
*May 20, 2014*

**Math**

well, not using the table .7^3 = .343 so you can be pretty sure that C is correct now let the digits of each of those three digit numbers be our test for example. If all three are seven or below, we got a win. There are twenty of those numbers. How many of them have all digits...
*May 20, 2014*

**geometry**

cos 81 = x/30
*May 20, 2014*

**geometry**

it goes up 8 feet while going horizontal distance sqrt(18^2+225) = 23.4 ft tan theta = 8/23.4 theta = 18.9 deg
*May 20, 2014*

**geometry**

tan theta = 17/29 Hey, draw a sketch for these problems so you can see what is opposite, what is adjacent and what is hypotenuse.
*May 20, 2014*

**physics**

power = voltage * current = 220 * .45 Watts by the way even at 220 volts, .45 amps does not sound like much to cook pizza.
*May 20, 2014*

**geometry**

sin 34 = d/180 d = 180 sin 34 = 100.6 ft
*May 20, 2014*

**physics**

output = work done = 530 * 4 = 2120 Joules by the way input = 200 * 15 = 3000 Joules
*May 20, 2014*

**physics**

luckily 6*10^5 is much less than light speed of 3*10^8 so not a relativity problem v = Vi + a t 5.94 * 10^5 = 2.95*10^5 + 2.7*10^14 t divide by 10^5 5.94 = 2.95 + 2.7*10^9 t 2.7 * 10^9 t = 2.99 t = 1.107 * 10^-9 seconds
*May 20, 2014*

**MATH HW HELP!!**

db/dt = .16 b db/b = .16 dt ln b = .16 t + c e^ln b = b = e^(.16 t +c) = C e^.16 t or more simply b = C e^.16 t when t =0 , e^.16 t = 1 so C = value when t = 0 b = 5 e^(.16*12) b = 34.1 grams
*May 20, 2014*

**physics**

m g h = work done to lift = 4*9.81*2.5 = 98.1 Joules
*May 20, 2014*

**Physics**

2.7 g/mL * 385 mL
*May 20, 2014*

**MATH HW HELP!!**

1.08^18 = 4 so $40,000
*May 20, 2014*

**AP chemistry**

the Al heats up the water cools down 25 * .897 * (40-0) = 100 * 4.186 * (Ti-40)
*May 20, 2014*

**math**

C = P + 32 M = 4 P - 38 C + P + M = 828 P + 32 + P + 4 P - 38 = 828 6 P -6 = 828 6 P = 834 P = 139 now go back and get C and M
*May 20, 2014*

**MATH HW HELP!!**

well, I can do it using daily but I bet continuous compounding will give the same answer to the nearest dollar :) anyway daily interest = .01825/365 = 5 * 10^-5 number of periods = 365 * 4 = 1460 1 + 5*10^-5 = 1.00005 1.00005^1460 = 1.07573 note this multiplier 1.07573 x = 25,...
*May 20, 2014*

**math**

You are welcome :)
*May 20, 2014*

**math**

d = 4/3 p d + p = 21 or 56 or whatever so (4/3) p + (3/3) p = 21 or 56 or whatever so (7/3) p = 21 or 56 p = (3/7) of whatever and d = 4/3 of that
*May 20, 2014*

**MATH HW HELP!!**

12/4 = 3% per period 7* 4 = 28 periods 1.03^28 = 2.288 so 2.288 x = 25,000 x = 10,927
*May 20, 2014*

**Chemistry**

You are welcome :)
*May 20, 2014*

**Chemistry**

Just look at the units: Joules = Joules/gram deg C * grams * deg C grams cancel deg C cancels left with Joules = .897 * 200 * 10 Joules = 1794 Joules
*May 20, 2014*

**math homework help**

r = .045/12 = .00375 number of periods = 12 *3.5 = 42 months 1.00375^42 = 1.170235983 times 250000 = 292,558
*May 20, 2014*

**Calculus**

Not necessarily for example if the data lies along a straight line the slope is the same everywhere You have to take a straight edge and try to make it tangent to your graphed curve at the origin. I do not know what your data looks like so can not say.
*May 20, 2014*

**Physics**

the period is 2 pi * square root of L/g we know the length however to find the period we need g on the surface of earth g is about 9.81 m/s^3 HOWEVER on the moon for example is is only about one sixth of that so the period will be sqrt 6 longer IN OTHER WORDS WE MUST KNOW g on...
*May 20, 2014*

**Science**

F = m a so a = F/m same F, m' = m/2 F = (m')a' a' = F/m' = F/(m/2) = 2 F/m = 2 a
*May 20, 2014*

**Physics**

I do not know but I can tell you the MAXIMUM efficiency which is that of a Carnot cycle High temp = 680 + 273 = 953 Kelvin Low Temp = 220 + 273 = 493 Kelvin Carnot efficiency = 100*(hot-cold)/hot = 100 (953-493)/953 = 48.3 %
*May 20, 2014*

**Science**

force down = m g - drag so m g-drag = m a where a is acceleration down a = g - drag/m so at the beginning, with low drag, the acceleration down is about 9.8 m/s^2 as the drag increases, the a goes down until terminal velocity is reached. That is when m g = drag when you open ...
*May 20, 2014*

**Science**

If the car was moving at 50 mph then you were moving at 50 mph. If the car de-accelerates to a stop suddenly and there is no back force on you, you continue to move at 50 mph (first law) Now the car is stopped and you are moving at 50 mph toward the windshield. It would be ...
*May 20, 2014*

**Physics**

w = omega = 16.3revs/min * 2 pi rad/rev *(1 min/60 s) = 1.71 radians/s v = omega r = 1.71 * 10 = 17.1 m/s Ac = v^2/r = 29.1 m/s^2 29.1/9.81 = 2.97 gs F = m a = 70 * 2.97 = 208 Newtons toward center There is no angular acceleration so no torque as far as I know.
*May 20, 2014*

**algebra**

OJ .5(8) + x = 2+x Total 8 + x so 2+x = .4(8+x) 2 + x = 3.2 + .4 x .6 x = 1.2 x = 2
*May 19, 2014*

**math**

(0,0) (2,0) (4,3) (2,3) well, you could cut it out of cardboard :) It goes to quadrant 2 The top face becomes the left face, so it faces a different way so d If you spin 90 deg left from quadrant 1, how could you be in quadrant 4 ?
*May 19, 2014*

**algebra**

If you did include them all (I wonder how many government candidates liked the program?) then .25 * 360 = 90 degrees
*May 19, 2014*

**algebra**

what on earth do the students who run for government have to do with this? Leave them out, part of another survey. We asked 230 students about this program evidently 110 of them liked it so (110/230)(360 degrees) = 172 degrees
*May 19, 2014*

**math**

for n = 5 coefs are 1 5 10 10 5 1 for example C(5,3) = 5!/[ 3!(5-3)!] = 5*4/2 = 10 so 1 x^5 + 5 x^4(-3) +10 x^3(-3)^2 +10x^2(-3)^3 +5x(-3)^4 +1 (-3)^5 = x^5 -15x^4+90x^3-270x^2+405x-243
*May 19, 2014*

**Asap please????**

I am not sure they could be counted there were so many local laws.
*May 19, 2014*

**algebra!!!**

I already did this tonight (x+1)(x-1) = x^2-1 = 40 x = sqrt 41 = 6.4
*May 19, 2014*

**Algebra**

12 a /(a^2 -3 a -10) if the denominator is zero, that is undefined and out of the domain so all we want to know is for what a is the denominator zero. It does not matter what the numerator is a^2 -3 a -10 = 0 a = [ 3 +/- sqrt (9 +40) ]/2 a = 10/2 or -4/2 so a = 5 or -2 are ...
*May 19, 2014*

**math**

You are welcome :)
*May 19, 2014*

**math**

Yes, A a REGULAR pentagon has rotational symmetry, but only if REGULAR
*May 19, 2014*

**Math**

The mode for the first one is 100 The mode for the second one is 95 first one ranges from 85 to 100 second one ranges from 81 to 100 mean of first is 94 mean of second is 94 remarkable ! median of first is 90 median of second is 95
*May 19, 2014*

**math**

takes too long calculate mean, the sum/10 calculate (x-mean)^2 for each x add them divide by 10 take the square root
*May 19, 2014*

**math**

(4/15)^2 = 16/225
*May 19, 2014*

**math**

4+3+5+2 = 14 two independent 4/14 draws (2/7)^2 = 4/49 = .0816
*May 19, 2014*

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

You are welcome :)
*May 19, 2014*

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

Of course if we had sketched a graph, we would have seen a straight line and not have bothered with the parabola :)
*May 19, 2014*

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

well, try a parabola since we have three points y = a x^2 + b x + c 1 = a (4) + b (2) + c 0 = a (16 ) + b(4) + c -1 = a(36) + b(6) + c subtract second from first 1 = -12 a -2 b subtract third from second 1 = -20 a -2 b subtract 0 = 8 a a = 0, this is a straight line 1 = -2 b b...
*May 19, 2014*

**fdr**

x by y x y = 100 23 x + 10 x + 20 y = cost = c 33 x + 20 y = c y = 100/x so 33x + 2000/x = c dc/dx = 0 for min = 33 -2000/x^2 33 x^2 = 2000 x^2 = 60.6 x = 7.785 ft y = 12.845 ft
*May 19, 2014*

**algebra**

(x+1)(x-1) = 30 x^2 = 31 x = 5.6
*May 19, 2014*

**math**

Yes, A is correct :)
*May 19, 2014*

**math**

Oh, sorry Jake, misunderstood your reply
*May 19, 2014*

**math**

Jake, your answer is A -5 --->+5
*May 19, 2014*

**math**

sketch it on a graph !!! Hint, straight back :) (-3,5)
*May 19, 2014*

**MATH**

if you rotate it 60 degrees (360/3), it looks exactly like it did before since there is a corner at every 60 degrees your answer to the second part is correct. Unlike circles, you can cover your flat roof with them with no leaks. http://mathforum.org/sum95/suzanne/whattess.html
*May 19, 2014*

**math**

first what is QR which is p? law of cosines p^2 = q^2 + r^2 - 2 p q cos P p^2 = 9.6^2 + 7.4^2 - 2(7.4)(9.6)cos 53 solve for p then law of sines sin R/7.4 = sin 53/ p
*May 19, 2014*

**algebra**

y = -3 + cos 2 pi (3/2pi) x or y = -3 + cos 3 x
*May 19, 2014*

**algebra 2**

7^(1/5) = fifth root of 7
*May 19, 2014*

**Science**

It did not result. The force caused the acceleration ! F = m a F = 3000*20 = 60,000 N
*May 19, 2014*

**Algebra**

total females = 80+80+70 = 230 80 of those in humanities first 80/230 = .348
*May 19, 2014*

**algebra**

1/sin (7pi/6) 7 pi/6 is pi/6 or 30 degrees below -y axis in quadrant 3 so sin 7 pi/6 = -1/2 inverse is csc = -2
*May 19, 2014*

**math**

sketch it in quadrant 2 y = 1 x = -1 tan theta = y/x = -1
*May 19, 2014*

**geometry**

1 meter by 0.2 meter boards? area board = .2 m^2 area floor = 50 m^2 50/.2 = 500/2 = 250
*May 19, 2014*

**Math**

when does 4 x = 2 pi , a full circle ? x = 2 pi/4 = pi/2 the single amplitude is given, 3
*May 19, 2014*

**Algebra**

d^2 = (y2-y1)^2 + (x2-x1)^2 d^2 = 5^2 + 12^2 = 13^2 (5 12 13 right triangle) 13
*May 19, 2014*

**math help**

x = -7717/335 y = -36738/335 z= 16662/335
*May 19, 2014*

**typo?**

-3 ??? x ???? +13y+29z=81 and what do you want? A solution using Gauss Jordan ? If so go to: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*May 19, 2014*

**algebra 1**

multiply both sides by -1 This changes the direction of the arrow 2 x/7 + 8 < 9 2 x/7 < 1 2 x < 7 x < 3.5
*May 19, 2014*

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