[Dreqsqse]

Simple equation really, trying to solve for y.
50 = sqrrt(XY) Also, how would you find the derivative of sqrrt(X)? I haven't done calc in 2 1/2 years and now I need it for my intermediate econ class.

[Sleflanna]

50 = sqrrt(XY)
50^2 = (sqrrt(XY))^2
2500 = XY
2500/X = Y

http://calc101.com/webMathematica/de...es.jsp#topdoit

Not sure about the derivative.

[MFSSCW2c]

Without more info', I don't see how you can go past what Turbo' has said.

[Gedominew]

dy/dx = -2500/x^2 ??

[IRMartin]

nvm. :S

[Dreqsqse]

WOWOWOW

[Deengealf]

Are you sure you can square both sides like that? If you put in constants it doesn't stay proportionate...

You can pretty much do whatever you want as long as you do it to both sides [yes]

[Evelinessa]

Are you sure you can square both sides like that? If you put in constants it doesn't stay proportionate...

For example 50 = sqrrt(16x4) would be 50 = 8 (6.25x larger) but if you squared both sides you would get 2500 = 64 (39x larger)

You more or less just answered your own question Lord_P. You can't just choose any x and y. For the values you chose you end up with 50=8 which is clearly not true. Any operations you do on that statement after that will clearly not work. Whatever x you choose, the value of y must be 2500/x for the statement to hold.

[Dreqsqse]

You more or less just answered your own question Lord_P. You can't just choose any x and y. For the values you chose you end up with 50=8 which is clearly not true. Any operations you do on that statement after that will clearly not work. Whatever x you choose, the value of y must be 2500/x for the statement to hold.

Wow I am not thinking this morning.

[Rqvtwlfk]

Simple equation really, trying to solve for y.

Also, how would you find the derivative of sqrrt(X)? I haven't done calc in 2 1/2 years and now I need it for my intermediate econ class.

Derivative of sqrt(x) is this:
same as (x)^(.5) so if it's d/dx then it's just .5x^(-.5)

[Dreqsqse]

How about ln(x) + ln(y) = K (constant) Solve for Y.

Given the point (20,12) exists on the graph

I can solve for k = about 5.48 but how do I get the y out of the ln expression? I thought I could just raise everything to the power of e but that is not working.

[bertanu]

How about ln(x) + ln(y) = K (constant) Solve for Y.

Given the point (20,12) exists on the graph

I can solve for k = about 5.48 but how do I get the y out of the ln expression? I thought I could just raise everything to the power of e but that is not working.

y = e ^(k-ln(x))

[bertanu]

Simple equation really, trying to solve for y. 50 = sqrrt(XY)

2500 / x = y

Also, how would you find the derivative of sqrrt(X)?

y = sqrt(x) = x^(1/2)

dy/dx = 1/(2 * x^(1/2))

[Dreqsqse]

y = e ^(k-ln(x))

God bless you. [thumbup]

[Rqvtwlfk]

That simplifies to y=(1/x)e^k

[nd90t3sf]

There is no solution to whY anyone would want to do math. Some assume its a genetic defect, and others believe it to be a form of insanity.

[Dreqsqse]

There is no solution to whY anyone would want to do math. Some assume its a genetic defect, and others believe it to be a form of insanity.

Believe me I onlY do it when I have to.