EighthMersennePrime

You have not use the commutative property to reorder the terms

Sure 

Anyways, the answer is 28.5714 seconds.

thee answer is...

$\frac{{x^2+x+3}}{{2x^2+x-6}}\ge 0?$

Answer is:

$x\in \big(-\infty ,-2\big) \cup \big( \frac{3}{2},+\infty \big)$