## Pages

News: Currently the LaTeX and hidden solutions on this blog do not work on Google Reader.
Email me if you have suggestions on how to improve this blog!

## Thursday, 18 August 2011

### Math GRE - #18

If we have $F(x)=\int_e^x{\log{t}dt}$ for all positive $x$, then $F'(x)=$

• $x$
• $\frac{1}{x}$
• $\log{x}$
• $x\log{x}$
• $x\log{x}-1$

Solution :

I decided to use this question because of it's similarity to the question I posted yesterday. Since the derivative of an integral is itself (FTC - Part I), we have $F'(x)=\frac{d}{dx}\int_e^x{\log{t}dt}=\log{x}.$

This webpage is LaTeX enabled. To type in-line formulae, type your stuff between two '\$'. To type centred formulae, type '$' at the beginning of your formula and '$' at the end.