Sunday

February 14, 2016
Total # Posts: 25,228

**Algebra 1**

19/2 = 9.5 !!!!
*January 4, 2016*

**Algebra 1**

( -2 , -19/2 ) ?
*January 4, 2016*

**Algebra 1**

Now you try. I did the last one.
*January 4, 2016*

**Algebra 1**

-x+2=3x-1 4x = 3 x = .75 then y = 1.25 so ( .75 , 1.25 )
*January 4, 2016*

**Science -- Check my Answer Plz**

you had typed 540*10^4 it should be 5.40 * 10^4
*January 4, 2016*

**Science -- Check my Answer Plz**

You will need 540 calories per gram water is 1 mL or 1 cm^3 per gram so I get 540 * 100 csl which is 5.40 * 10^4 cal I hope B is a typo and should be 5.40*10^4
*January 4, 2016*

**Science -- Explaination on Heat Capacity?**

You are welcome, good luck.
*January 4, 2016*

**Science -- Explaination on Heat Capacity?**

Oh my, you question is not about heat capacity but about the latent heat of fusion of water. to melt one gram of ice at 0 deg C requires 224 Joules or 79.8 Calories so to melt 10 grams requires 2240 Joules or 798 calories (so pick 800) specific heat capacity is when there is a...
*January 4, 2016*

**Math**

number of spots for players over the season = 42 * 9 = 378 378/14 = 27 games for each player
*January 4, 2016*

**math**

of course now that you mention it, adding a number to itself is kind of like multiplying it by two if it were six instead of five 6+6 = 12 2*6 = 12
*January 4, 2016*

**math**

2 n = n + 5 ? n = 5
*January 4, 2016*

**Geometry (again)**

You could maybe see if a^2+a^2 = c^2 or in the trapezoid if the two diagonals are equal
*January 4, 2016*

**Algebra**

T(t)= 12 + 3 (t-7)
*January 4, 2016*

**Rational Numbers**

Well done !
*January 4, 2016*

**Rational Numbers**

You are welcome.
*January 4, 2016*

**Rational Numbers**

A. Sometimes 22/7 is used for pi HOWEVER it is only an approximation. There are no two whole numbers you can divide and get pi. pi is therefore IRRATIONAL B no way, irrational C no way, irrational D 4/3 YES, finally
*January 4, 2016*

**U.S. History**

.... and now ?
*January 4, 2016*

**Math**

let u = sin x so du/dx = cos x y = cos^-1 (u) dy/dx = - [1/(1-u^2)^.5 ] du/dx = -[ 1/cos x] cos x = -1 we agree
*January 4, 2016*

**math**

540/27 = 20
*January 4, 2016*

**physics**

bullet mass + wood mass = 2.107 kg potential energy if up 0.4 meter: I assume this is along the circumference so .4 = theta * 2 = theta = .2 radians = 11.5 degrees distance up from bottom = 2 (1-cos theta) = .0803 meters so energy at top = m g h =2.107*9.81*.0803 = 1.66 Joules...
*January 4, 2016*

**Math Complicated**

You are welcome.
*January 4, 2016*

**Math Complicated**

Yes, you have it :)
*January 4, 2016*

**Math**

(24/48)(x^4/x^2) (y^2/y) (1/2) x^2 y
*January 4, 2016*

**physics**

vertical problem: v = Vi - 9.81 t v = 0 at the top t = Vi/9.81 at the top which is 100 meters h = Vi t - 4.9 t^2 100 = Vi^2/9.81 - .5*9.81 (Vi^2/9.81^2) 100 = .5Vi^2/9.81 Vi = 44.3 m/s T = angle up from horizontal sin T = 44.3/50 T = 62.4 degrees t = 2 * Vi/9.81 = 2*44.3/9.81...
*January 4, 2016*

**US History**

nope: http://www.dummies.com/how-to/content/what-is-the-presidents-cabinet.html
*January 4, 2016*

**Science**

I agree with YRN on all others
*January 4, 2016*

**Science**

5 is C
*January 4, 2016*

**Science**

Al is 27 g/mol so we have 3 * (13.5/27) * 6 *10^23 electrons lost
*January 4, 2016*

**Science**

M = metal we have MCl2 1 mol chlorine and 1/2 mol of metal 35.5 g chlorine in a mol 111 - 35.5 = 75.5 g of M so M is 75.5 * 2 = 151 g/mol maybe Europium
*January 4, 2016*

**Physic**

sorry, no it is ok well, for a plane wave d^2y/dx^2 must be (1/v^2)d^2y/dt^2 if y = x^2 + v^2 t^2 dy/dx = 2x d^2y/dx^2 = 2 dy/dt = 2 v^2 t d^2y/dt^2 = 2 v^2 2 = (1/v^2) 2 v^2
*January 4, 2016*

**Physic**

well, for a plane wave d^2y/dx^2 must be (1/v^2)d^2y/dt^2 if y = x^2 + v^2 t^2 dy/dx = 2x d^2y/dx^2 = 2 dy/dt = 2 v^2 t d^2y/dt^2 = 2 v^2 so it is not and you should have written x^2 + (1/v^2) t^2
*January 4, 2016*

**Science**

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html
*January 4, 2016*

**physics**

west momentum = 1500 * 90 north momentum = 1400 * 72 final west momentum = 2900 Vwest final north momentum = 2900 Vnorth final = initial speed = sqrt(Vwest^2 + Vnorth^2) tan angle west of north = Vwest/Vnorth
*January 4, 2016*

**Math**

upstream speed = u - c downstream speed = u + c d = (u-c)(3.5) = (u+c)(2.1) but c = 3 so (u-3)(3.5)=(u+3)(2.1) 3.5 u - 10.5 = 2.1 u + 6.3 1.4 u = 16.8
*January 4, 2016*

**Another Calculus help plz**

I do not know if you mean tan (x/2) or (1/2) tan x Parentheses are important. I will just do y = tan x = sin x / cos x perhaps that will get you going. dy/dx = (cos^2 x + sin^2 x)/cos^2 x = 1/cos^2 x
*January 4, 2016*

**Calculus help plz**

cos^2 mx dx ? = mx/2 + sin(2mx) / 2m
*January 4, 2016*

**Math**

22.05 = 1960 (r/4) 1960 r = 88.20 r = .045 so 4.5 %
*January 4, 2016*

**Math**

3 * .04 * 820
*January 3, 2016*

**Math**

.75 * 52
*January 3, 2016*

**Science (Mrs.sue please help)**

Yes.
*January 3, 2016*

**Need the picture**

Without the picture there is not much hope of help.
*January 3, 2016*

**Algebra**

slope of zero means constant y (4,9) and (3,9) and calling the second coordinate x is presumably done to confuse the student.
*January 3, 2016*

**Physic - ah got it !**

http://www.thefreedictionary.com/physic
*January 3, 2016*

**Physic**

By the way is a physic something you take for a stomach ache?
*January 3, 2016*

**Physic**

work = force in the direction of motion * distance normal force down = weight - tension component up = m g - F sin 23 friction force = .33(mg-F sin 23) drag force = F cos 23 no accelration so friction force = drag force F cos 23 = .33 (mg-F sin 23) solve for F we want the ...
*January 3, 2016*

**Science**

model ? example Bohr atom ?
*January 3, 2016*

**Calculus**

http://mathworld.wolfram.com/Semicircle.html look at integration for weighted mean, then divide by area. pi r^2/2
*January 3, 2016*

**Calculus**

4 r/3pi is the semicircle do the outer one, then subtract the inner one. See for example: http://en.wikipedia.org/wiki/List_of_centroids
*January 3, 2016*

**math**

(-1)^ even power = 1
*January 3, 2016*

**Math**

it is 4, the distance from west 2 to east 2 :)
*January 3, 2016*

**Math**

n^2 - 4 = 21 + 9 n n^2 - 9 n -21 = 0 (n-7)(n+3) = 0 n = 7 so the smallest is 5
*January 3, 2016*

**Math**

They are POSITIVE, odd numbers are OUT so they differ by TWO n-2 , n , n+2 (n-2)(n+2) = 21 + 9 n
*January 3, 2016*

**math**

x^4 - 5 x^3 + 5 x^2 + 4 x - 61 = 0 find the roots try http://www.wolframalpha.com/input/?i=x^4+-+5+x^3+%2B+5+x^2+%2B+4+x+-+61+%3D+0+&x=5&y=5
*January 3, 2016*

**Algebra**

55 t +120 - 40 t = 135 15 t = 15 t = 1 hour at 55 so 55 miles on highway 2 hours at 40 = 80 miles on dirt
*January 3, 2016*

**Algebra**

55 t + 40 (3-t) = 135
*January 3, 2016*

**math**

I will leave you to get s now
*January 3, 2016*

**math**

.866 s = 950 sin h - 90 .866 s = 1645 cos h ---------------------subtract 950 sin h = 1645 cos h + 90 or 950 sin h - 1645 cos h = 90 for various values of h h , left side 60 , .224 61 , 33.4 62 , 66.5 63 , 99.6 so steer 62.5 degrees west of south 65 , 165 70 , 331
*January 3, 2016*

**math**

He must stay on a course of S 60 W. We must find the heading :) h is degrees heading west of south say his speed over the ground is s then west speed over ground = s sin 60 = 950 sin h - 90 and south speed over ground = s cos 60 = 950 cos h so .866 s = 950 sin h - 90 .5 s = ...
*January 3, 2016*

**Does not make sense**

You say Ruth has 130 then ask how much she has.
*January 3, 2016*

**Geography (Ms.Sue ) Help**

Interesting - stress seems to lead to more babies. War torn Afganistan is top at 2.4 followed by Maldives threatened by flooding at 1.9 Quiet but lonely Nepal at 1.2 Quiet Sri Lanka (since the tsunami) lowest at 0.8
*January 3, 2016*

**Geography (Ms.Sue ) Help**

http://www.google.com/search?q=population+growth+nepal&ie=utf-8&oe=utf-8 http://www.google.com/search?q=population+growth+afganistan&ie=utf-8&oe=utf-8 http://www.google.com/search?q=population+growth+sri+lanka&ie=utf-8&oe=utf-8 http://www.google.com/search?q=population+growth+...
*January 3, 2016*

**math**

6-4 5-3 4-2 3-1 4-6 3-5 2-4 1-3 so 8 work out of how many 6 * 6 I think or 36 so I get 8/36 = 2/9 see: http://www.freemathhelp.com/rolling-dice.html
*January 3, 2016*

**physics**

Ah, did not think of that :)
*January 3, 2016*

**physics - No way - directions not defined**

Is it pushed up or down the slope? Is that 20 m/s up slope or down slope? I will assume both are UP and you will have to get it straight yourself. weight component down slope = m g sin 37 = 80 * 9.81 * sin 37 = 472 N If you are pushing up with 400 N, you lose, at least on ...
*January 3, 2016*

**chemistry**

Maybe lea nitrate ?
*January 3, 2016*

**math**

a7 = a + d(6) = 21 {so 2a+12 d = 42} sum of first 13 = (13/2)(2a + 12d) = (13/2)(42) = 13 * 21 = 273 look at: http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
*January 3, 2016*

**Calculus pz help urgently**

-.25 cos (2x-pi/4) - .25 x sqrt 2 + c
*January 3, 2016*

**Calculus pz help urgently**

note we no longer have sine curves with zero mean value but now have an average plus a cosine curve with twice the frequency.
*January 3, 2016*

**Calculus pz help urgently**

note sin pi/4 = sqrt2/2 -.25 cos (2x-pi/4) - .25 sqrt 2
*January 3, 2016*

**no, wrong**

I guess maybe you mean sin x cos(x-pi/4)dx sin x cos y = .5 sin (x+y) + .5 sin (x-y) (remember "beat frequency" ) so .5sin ( 2x-pi/4)dx + .5sin (pi/4)dx
*January 3, 2016*

**Calculus pz help urgently**

I guess maybe you mean sin x cos(x-pi/4)dx sin x cos y = .5( sin x +sin y) + .5 (sin x - sin y) (remember "beat frequency" ) so .5(sin x + sin(x-pi/4)dx + .5(sin x - sin(x-pi/4)dx ---------------------------- add (oh my) sin x dx -cos x + c
*January 3, 2016*

**sorry, do not know**

As far as I know zero to the anything is zero.
*January 3, 2016*

**Math**

You are welcome.
*January 3, 2016*

**Math**

a) 2/7 b) 5/7 * 9/24 c) assume 6 am for maximum inconvenience so 8/24
*January 3, 2016*

**math**

20/16 divide top and bottom by 4 5/4
*January 3, 2016*

**math**

still 5/4
*January 3, 2016*

**Math**

c T = wavelength - 3 m (1/4)3 = .75 meters = 750 cm
*January 3, 2016*

**Math**

how long would a (1/4) wave antenna be? (use c = 3*10^8 meters/second)
*January 3, 2016*

**math- HELP!**

$2600 initial at 8% compounded continuously
*January 2, 2016*

**Do you get it now?**

Get the idea? Richer # = log of amplitude. so you take 27 times the antilog and then take the log of that
*January 2, 2016*

**Math Exponetial Function Problem Question?**

here slowly Richer number = 3.2 3.2 is log of amplitude A log A = 3.2 10^logA = A = 10^3.2 = 10^3 * 10^.2 so A = 10^3 * 1.5848 Now Multiply THAT by your 27 B = 10^4 * 4.27921 log B = log 4 + log 4.27921 = 4.631 which is your new Richter #
*January 2, 2016*

**Math Exponetial Function Problem Question?**

You multiply the 27 by the amplitude, not the log of the amplitude. then take the log of the new bigger amplitude for the new Richter number.
*January 2, 2016*

**Math Exponetial Function Problem Question?**

No, log scale I answered this yesterday http://www.jiskha.com/display.cgi?id=1451681946
*January 2, 2016*

**Spanish**

whew :)
*January 2, 2016*

**Math**

I did this not long ago http://www.jiskha.com/display.cgi?id=1451681946
*January 2, 2016*

**Math**

hint here: http://www.jiskha.com/display.cgi?id=1451675195
*January 2, 2016*

**Math**

You are welcome.
*January 2, 2016*

**Math**

Suspect you mean 2^(2x+3) = 80 that means (2x+3)log 2 = log 80 (2x+3) = 6.32192 2x = 3.32192 x = 1.6609
*January 2, 2016*

**Math**

19 * 100 / 27 = 70 % is his score in percent. I do not know if you are using letter grades or whatever.
*January 2, 2016*

**Math**

I think your answer is fine. So is the 3^2 = 9 one.
*January 2, 2016*

**Math**

well 9^x = 3^(2x) so log^-1 (2 x log 3) is a perfectly good answer. So is Log^-1(xlog(9)) They are the same :)
*January 2, 2016*

**Math**

Yes, but count brackets. I try to use different ones log^-1[ x(log 7 - log 8) ]
*January 2, 2016*

**Calculus**

It is just that sqrt (a^2-b^2) is not a - b
*January 2, 2016*

**Calculus**

By the way, you tried x^3 as well :..... sqrt (1-x^6) into 1^(1/2)- x^(3) ..."
*January 2, 2016*

**Calculus**

Why should I not let u = anything I choose ? LOL I see an x^6 and an x^2 so I tried x^3
*January 2, 2016*

**Calculus**

sin^-1 u + c so sin^-1 x^3 + c
*January 2, 2016*

**Calculus**

sqrt (1-x^6) into 1^(1/2)- x^(3) I do not think so I will try the easy way u = x^3 du = 3 x^2 dx so I have du/ sqrt (1-u^2)
*January 2, 2016*

**Calculus**

B and D
*January 2, 2016*

**Calculus**

In C, that nasty x cancels
*January 2, 2016*

**Calculus**

the problem with B and D is that dx = dy/f(x) so the substitution does not get rid of the x
*January 2, 2016*