Saturday
July 4, 2015

Posts by Damon


Total # Posts: 21,421

Calculus
You already did it. f(0) = 0 f(pi) = 1 etc, at the four points where the derivative is zero
June 15, 2015

Calculus
You mean cos x sin x = 0 when cos x = 0 or when sin x = 0 when cos x = 0, then sin x = 1 and you have a max when sin x = 0, then cos x = 1 and you have a min
June 15, 2015

Calculus
LOL, |sin x| is always </= 1 it is at + pi/2 and 3 pi/2 where cos x , the derivative of sin x, is 0
June 15, 2015

physics
I also get -0.0391
June 14, 2015

physics
I am not going to answer the others because they are really the same as this one. For example if you have charges 2q and - 2q within a closed surface, the net E flux out is zero.
June 14, 2015

physics
The Gauss' Law flux = integral E dot dA = Q/epsilon The Gauss law states that electric net flux through any Gauss surface is directly proportional to the net charge enclosed by the surface where is permittivity of vacuum
June 14, 2015

physics
Huh ?? Gauss! Does not matter shape or size of surrounding surface. Flux out proportional to charge inside.
June 14, 2015

physics
if you have Q per square meter (maybe call it sigma) net flux out of the square meter is Q/epsilon Looking at both sides of the sheet we have surface area of the enclosure = 2 square meters flux = E * 2 m^2 = Q/epsilon
June 14, 2015

Algebra2
2(3x-5)= 16 6x -10 = 16 6 x = 26 x = 13/3 and 2(-3x+5) =16 -6x + 10 = 16 6 x = -6 x = -1
June 14, 2015

geometry
meters, seconds, g = 9.8 m/s^2 h = Vi t - 4.9 t^2 tan q = h/x so x tan q = Vi t - 4.9 t^2 observe angle q at time t solve for x at time t or if Vi is the unknown solve for Vi at x and t then solve for h
June 14, 2015

Calculus
I have no idea where Q is
June 13, 2015

Calculus
4 s + 2w + 4w = 4 s + 6 w = 17 A = s^2 + w(2w) = s^2 + 2 w^2 s = (17-6w)/4 A = (1/16)(17-6w)^2 + 2 w^2 dA/dw = 0 at min 0 = (1/8)(17-6w)(-6) = 4 w (3/4)(17-6w) = 4 w 3 (17-6w) = 16 w 51 - 18 w = 16 w 34 w = 51 w = 51/34 = 1.5 then find s and w and 2 w
June 13, 2015

Pre-Calculus
we want (x-h)^2/a^2 +(y-k)^2/b^2 = 1 now x-h = a cos t so (x-h)^2 = a^2cos^2 t so (x-h)^2/a^2 = cos^2 t similarly (y-k)^2/b^2 = sin^2 t so (x-h)^2/a^2 + (y-k)^2/b^2 = cos^2 + sin^2 = 1
June 13, 2015

typo
but we know t = 19.5/x should be t = x/19.5 of course
June 12, 2015

Physics
Horizontal, no force, u =constant so x = 19.5 t so t = x/19.5 Vertical, f = -9.81 m/s^2 * mass = m a so a = acceleration = - 9.81 so a = -9.81 v = Vi - 9.81 t v = 15.4 - 9.81 t then y = initial height + 15.4 t - 4.9 t^2 call initial height of quarterback hand Hi y = Hi + 15.4 ...
June 12, 2015

Physics
I do not care if she is thin or fat. falls 9 meters, how long? h= (1/2) g t^2 18 = 9.8 t^2 t = 1.36 falling goes 1.75 meters horizontal in 1.36 seconds 1.75 = u t = u (1.36) u = 1.29 m/s horizontal speed
June 12, 2015

Physics
This is not Physics. tourist runs distance d bear runs distance (d+31.1) same time t d = 3.24 t d+31.1 = 4.5 t so d + 31.1 = 4.5(d/3.24) 3.24 d + 100.7 = 4.5 d d = 80 meters max this tourist is no track star :(
June 12, 2015

Alg 2 HELP!
-5, 1 , 2 http://www.wolframalpha.com/widgets/view.jsp?id=a7d8ae4569120b5bec12e7b6e9648b86 (right away you should see that one works, then you have a quadratic) domain of parabola is all real x. (range is another story) g = (2x+1)^2 + 3(2x+1) now you multiply out and collect ...
June 12, 2015

alg 2
Yes it is (x+4)(x^2+9) x = -4 you know however x^2+9 = 0 x^2 = -9 is x = +3i or x = -3i (not rational real)
June 12, 2015

Alg
http://www.mathportal.org/calculators/polynomials-solvers/polynomial-graphing-calculator.php
June 12, 2015

math
4 is not it I think but 3 kind of looks reasonable
June 11, 2015

math
in this system of units, remembered only by ancient mathematicians, g = 32 ft/s^2 approximately. so a = - 32 v = Vi - 32 t = 38 - 32 t h = Hi + Vi t + (1/2) a t^2 0 = 30 + 38 t - 16 t^2 or 16 t^2 - 38 t - 30 = 0 8 t^2 -19 t -15 = 0 solve that quadratic for t, use the positive ...
June 11, 2015

geometry
think square 3 meters on each side area = 3*3 = 9 then square 6 meters on a side, double area = 6*6 = 36 or four times length ratios = 2 area ratios = 4 2^2 = 4
June 11, 2015

geometry
areas scale as square of length ratio so 5/2 in area ---> sqrt(5)/sqrt(2) in length so 25 * sqrt 2/sqrt 5 = 15.813883
June 11, 2015

Bayes' Theorem
say 100 students 40 from Ka .04*40 = 1.6 fails 50 from Ill .02 * 50 = 1 fails 10 from Oh .06 * 10 = .6 fails total failures = 1.6+1+.6 = 3.2 That is 3.2/100 = 3.2 % = .032 3.2 fail, 1.6 of whom are from Ka 1.6/3.2 = .5 or 50% BUT you said use Bayes so P(Ka if failed) =P(failed...
June 11, 2015

physics
melting ?
June 10, 2015

Math117A
height/shadow = 4.2/12.6 = 20.4 /x 4.2 x = 12.6 * 20.4 x = 12.6 * 20.4 / 4.2 x = 61.2 check, the shadow should be about three times as long as the object is high in this problem. It is.
June 10, 2015

algebra2
3 x - 10 x - 20 = 13 - 7 x - 7 x = 33 - 7x 0 = 33 no solution please try these and post your attempt. I am getting bored.
June 10, 2015

algebra2
x = -22 You can solve that :) Now Karla, try the problem before posting it.
June 10, 2015

algebra2
10 x + 30 = 10 x + 30 ANY value of x works INFINITE number of solutions BUT what if it were 10 x + 30 = 10 x + 40 then there would be no solutions at all
June 10, 2015

Finite Math
You are welcome :)
June 10, 2015

Finite Math
100 students 50 had pre calc - 15 got A, 35 not A 50 no pre cacl - 10 got A, 40 not A sure looks like 35 of the hundred :)
June 10, 2015

algebra2
2 x = 145 so x = 145/2 the end
June 10, 2015

chemistry
by the way http://www.quora.com/How-much-water-can-you-split-into-hydrogen-and-oxygen-using-electrolysis-with-one-kilowatt-hour-of-electricity
June 10, 2015

chemistry
3 hours * 3600 seconds/hour = 10800 seconds 10800 seconds * 0.1 amps = 1080 Coulombs H2O --> 2H+ + O-- 1 mol electrons = 96,500 Coulombs so 1080 C * 1/96500 = .0112 mol electrons looking at equation, we need 2 mol electrons for every mol of H2 so we get .0056 mol of H2 ....
June 10, 2015

science
Draw a sketch diagram 2 * 5 cos 30 = 8.66 m/s at 30 degrees to each
June 10, 2015

Chemistry
Ni is about 68.7 grams per mol. so 138/68.7 = 2.008 mol of Ni that is 2.008 mol * 6.02*10^23 atoms/mol = 12.1 *10^23 atoms (quite a few )
June 10, 2015

Chemistry
by the way iron is also about 8 times as dense as water (1 g/cc or 1000 kg/m^3) and aluminium is less and concrete is about half. That gives you a bit of a check.
June 10, 2015

Chemistry
That looks right to me.
June 10, 2015

Math
Iris, You had your choice of 6% compounded or 13% simple for four years. 13% simple wins.
June 10, 2015

Math
when you compound at interest rate x percent every period you multiply by (1+x/100) so for 4 years at 6% multiply four times by (1 + .06) which is the same as multiply by 1.06^4 if it were 6% per year compounded monthly thet would be 6%/12 per month .06/12 = .005 so we would ...
June 10, 2015

Math
Well how did you do it really ?
June 10, 2015

Math
13% is so much more than 6% that the compounding will not catch up for many years.
June 10, 2015

Math
1.06^4 = 1.26248 *2000 = 2524.95 so earned 524.95 0.13 * 4 =.52 .52 * 2000 = 1040 so earned 1040.00 go with the 13 % simple
June 10, 2015

Chemistry
how many Joules do you need? Joules needed = specific heat * mass * change in temp then watts * seconds = Joules needed
June 9, 2015

Chemistry
C * m (60-40) = C * 50 (40-20) so m = 50 grams or .050 Kg
June 9, 2015

History
Should I laugh or cry?
June 9, 2015

Calc 1
sure looks like it to me
June 9, 2015

Calc 1
Hey, you can google too :)
June 9, 2015

Calc 1
not necessarily http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CEgQFjAI&url=http%3A%2F%2Fwww.mathsisfun.com%2Fcalculus%2Fdifferentiable.html&ei=2wt3VbzLIMGasQXEoIEI&usg=AFQjCNG-Oqx8EjGrCBl7-c8WA0YYFZ28ag&sig2=WquSfxU_It3cBOBGKCGExg&bvm=bv....
June 9, 2015

Calc 1
True, if more then not a function http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDMQFjAC&url=http%3A%2F%2Fwww.milefoot.com%2Fmath%2Fcalculus%2Flimits%2FFindingAsymptotes12.htm&ei=ZAt3Ve-jC4mQsAXlt4HgDQ&usg=AFQjCNHZjboUch1fdELGYXBuIZC-Tnu_rg...
June 9, 2015

Calculus 1
well, if x = .99 I get 1.50 if x = .999 then 1.500 that is because numerator = (x-1)(x+2) denominator = (x-1)(x+1) so what we really have is (x+2)/(x+1) which is 1.5 at x = 1 It is true that the original function is undefined at x = 1
June 9, 2015

physics
They are brakes. after 5 sec at constant v Vi = 20 v = 20 + a t where t is total time - 5 v = 0 when t = 8 so 0 = 20 + a (8) a = -20/8 = - 5/2 so v = 20 - (5/2) t = 20 - (5/2)(time - 5)
June 9, 2015

Math
11 with vanilla + 11 with chocolate = 22 , right
June 9, 2015

Calc 1
y at x = 5 = a then y^2 = 25 all right when x = 5
June 9, 2015

math
total N = 330 + 900 = 1230 Total E = 640 + 370 = 1010 so sqrt (1230^2 + 1010^2)
June 9, 2015

Calc 1
nope, what if y = L (x-a)/|x-a|
June 9, 2015

Math
pi is actually about 22/7 This problem is a lot harder than it looks because you should really pack the discs in a hexagonal pattern but I suspect the best we can do is put squares around the circles. 100 /14 = 7.14 so 7 lengthwise 60/14 = 4.28 so 4 that direction 7 * 4 = 28 ...
June 9, 2015

math trigonometry
I have no reason to believe it is true.
June 9, 2015

SCIENCE
A to B speed = 300m/170 seconds velocity = speed if that direction is + then A to C distance = 300 + 100 = 400 average speed = 400/230 but total displacement = +300 - 100 = 200 so'=average velocity = 200/230
June 9, 2015

math
I do not think so. Sketch a graph.
June 8, 2015

Physics
x = 1.40 t^2 - .0505 t^3 at t = 0, x = 0 at t = 1.91, x =1.40 * 1.91^2 - .0505 * 1.91^3 = 4.755 meters so 4.755 meters in 1.91 seconds = 2.5 m/s do the others the same way, find out how far it went in the time interval and divide by the time interval
June 8, 2015

statistics
5/15 * 4/14
June 8, 2015

MATH
x/10 = 37/8 so x = 370/8 (370/8)/16 = 370/128 = 2 114/128 = 2 57/64
June 8, 2015

math
2* (1/2) pi (1) + 2*3 maybe ?
June 8, 2015

Math help please.
7 yes 8 A because -3 * -2 = +6
June 8, 2015

Math help please.
6)-2r(8r+5) A)-16r^2+5 B)-16r+10 C)-16r-10r** D)-16r-10 Nah, -16 r^2 - 10 r probably c but a typo
June 8, 2015

Math help please.
7^4/7^2 = 7^2 = 7*7 = 49 right
June 8, 2015

Math help please.
4) 50 A)0 B)5 C)1 D)-5 Perhaps you mean 5^0 but anything^0 = 1
June 8, 2015

Math help please.
3) 4^4/4^6 4 - 6 = -2 4^-2 = 1/4^2 = 1/16 A)-16 B)16 C)1/16 D)-1/16
June 8, 2015

Math help please.
2) h^14/h^5 14 - 5 = 9, not 19
June 8, 2015

Math help please.
1) x^9/x^2 = x(9-2) = x^7
June 8, 2015

maths
if the second hand moves 180 degrees, that is half a minute .5 min (360 degrees/60 min) = 3 degrees
June 8, 2015

Calculus
Oh, go with what Steve said.
June 8, 2015

Calculus
profit = p(x) - C(x) = 50-.01 x - 10 - 2x = 40-2.01 x max at x = 0 I bet you have a typo though.
June 8, 2015

math
well one way is a parabola write a parabola that goes through (4,1) (6,1.5) and (8,6) first (4,3) (6,0) and (8,0) Y1 = 3(x-6)(x-8) /(4-6)(4-8) = 3(x^2 -14 x + 48)/ 8 second (4,0)(6,1.5)(8,0) Y2 = 1.5 (x-4)(x-8)/(6-4)(6-8) = -(1.5 x^2 -18 x +48)/4 third Y3 = 6(x-4)(x-6)/(8-4)(8...
June 7, 2015

math
whoops, I dd it for 300 of fence, not 200
June 7, 2015

math
if two internal petitions the 4 x needed for cross fencing + 2 L needed for length P = 4 x + 2 L =300 or L = 150 - 2 x A = x L = x (150 - 2 x) = 150 x - 2 x^2 if you know calculus: dA/dx = 0 at max = 150 - 4 x so x = 150/4 = 37.5 then L = 150 -2*37.5 = 75 AREA = 37.5*75 = 2812...
June 7, 2015

COLLEGE MATH
I do not know what level of math you are at. If calculus then dC/dx = 0 at min = .4 x =96 so x = 240 If Algebra 2 level then complete the square to find vertex .2 x^2 - 96 x = -12095 x^2 - 480 x + 240^2 = - 60475 x^2 - 480 x + 240^2 = - 2875 (x-240)^2 = -2875 so x = 240 and C...
June 7, 2015

Another math related question
4/10 * 7/15 = 14/75
June 7, 2015

Calculus
you have P = 2 x + 154/x BUT you took the derivative incorrectly P' = 2 -154/x^2 so for min or max 0 = 2 - 154/x^2 or x^2 = 77 NOTE d/dx (1/x) = -1/x^2
June 7, 2015

physics
any acceleration is down the slope, perpendicular to the force we are interested in. That normal force is the component of weight normal to the hill surface which is m g cos 25
June 7, 2015

physics
If two capacitors are in parallel, they hold more charge for a given voltage. We know that C = Q/V here C1 = Q1/V C2 = C2/V C1 + C2 = (Q1+Q2)/V so final C = C1 + C2 In other words, if in parallel, add capacitances because you add charges per unit voltage
June 7, 2015

to damon
You are welcome - good luck !
June 7, 2015

algebra
ah ham you know Pascal's triangle so you know binomial theorem after all now call a = 4 y call b = x then (a+b)^4 = a^4 + 4 a^3b + 6 a^2b^2 + 4 a b^3 + b^4 which is 256 y^4 + 256x +6 (4y)^2 x^2 etc
June 7, 2015

maths
sin PQR = 300/600 = 1/2 so PQR = 30 degrees that is 30 degrees south of west or 60 degrees west of south which id a compass bearing of 180 + 60 = 240 degrees clockwise from north cos 30 = RQ/600 RQ = 520 m
June 7, 2015

algebra
no imagine (x-y)^2 it is not x^2 - y^2 but x^2 - 2 x y + y^2 You need the "binomial theorem" If you have learned it your problem is straightforward, follow the recipe. If you have not had it in your course, I feel for you because you will have to do it step by ...
June 7, 2015

algebra
(x^4 y^5)^5 = (x^4)^5 (y^5)^5 = x^20 y^25
June 6, 2015

Physics
do the fall first v = g t 44 = 9.81 t t = 4.49 seconds falling now the up part Vi = 24.4 v = Vi - g t 0 = 24.4 - 9.81 t where t is time rising t = 2.49 seconds upward so 4.49 + 2.49 seconds
June 6, 2015

Physics
Yes, your wording indicates that you need help. You not only have to heat the water to 100 deg C You have to BOIL IT as well ! so look up the specific heat of water, call it C then LOOK UP THE HEAT OF VAPORIZATION of water. then heat in = 2 * specifc heat * (100-37) + 2 * heat...
June 5, 2015

6th Grade Probability
1/4 of the times you play (1/4)36 = 9
June 5, 2015

Physics
wavelength = twice string length to get node at each end and bulge in middle. L = (1/2) wavelength wavelength = speed * period = speed/frequency so L = (1/2) v/f
June 4, 2015

Algebra
check below http://www.jiskha.com/display.cgi?id=1433381900
June 4, 2015

Physics
You are welcome.
June 4, 2015

Physics
The tension and mass density determine the speed of the wave along the string. The input frequency is the wave frequency wavelength = speed * period = speed/frequency so frequency, tension and mass density right
June 4, 2015

Physics
A yes B yes C No D yes I agree.
June 4, 2015

Algebra
L^2 + w^2 = d^2 (d-3)^2 + (d-8)^2 = d^2 d^2 - 6 d + 9 + d^2 -16 d + 64 = d^2 d^2 - 22 d + 73 = 0 d = [ 22 +/- sqrt(484 - 292) ] / 2 d = [ 22 +/- 13.9 ] / 2 d = 17.9 or 8.1 8.1 is impossible if the area is 84 so d = 17.9 ------------------- check then w = about 10 and L = about...
June 4, 2015

Math
66 = 2*33 = 2 * 3 * 11 99 = 3 * 33 = 3 * 3 * 11 20 = 2*10 = 2 * 2 * 5 etc, boring
June 4, 2015

Math
look at b^2 - 4 a c if +, then two intercepts if 0, then just grazes the x axis, one intercept if -, then never hits the axis, imaginary roots only if a x^2 + b x + c = 0 then - (a x^2 + b x + c) = 0 is the same because +0 = -0
June 4, 2015

math
sin^4⁡x-cos^4⁡x = (sin^2 x+cos^2 x)(sin^2 x -cos^2 x = 1 (sin^2 x - cos^2 x) = 2 sin^2 x - 1
June 4, 2015

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