The Student Room Group

Diff of this equation

Just checking the answer to a question:

y=(lnx)/x => dy/dx=(1-lnx)/x^2

Done using quotient and u=lnx, du/dx=1/x, v=x, dv/dx=1
Reply 1
xdydx+y=1x\displaystyle x\frac{dy}{dx}+y=\frac{1}{x}

dydx=x2yx\displaystyle\frac{dy}{dx}=x^{-2}-\frac{y}{x}

dydx=x2lnxx2=1lnxx2\displaystyle\frac{dy}{dx}=x^{-2}-\frac{lnx}{x^2}=\frac{1-lnx}{x^2}

looks fine
Reply 2
Original post by Pheylan
xdydx+y=1x\displaystyle x\frac{dy}{dx}+y=\frac{1}{x}

dydx=x2yx\displaystyle\frac{dy}{dx}=x^{-2}-\frac{y}{x}

dydx=x2lnxx2=1lnxx2\displaystyle\frac{dy}{dx}=x^{-2}-\frac{lnx}{x^2}=\frac{1-lnx}{x^2}

looks fine


Good stuff. I also appreciate the artistic quality of your sig.
Original post by daftndirekt
Good stuff. I also appreciate the artistic quality of your sig.

That's an interesting way to put it. :p:

Quick Reply

Latest