$3x-10xy+13y-4xy+2x^2$

$\frac{6.4}{2.6}$

$\lim_{x\to\:0}\left(\frac{x^3+2x}{1-\:e^{2x}}\right)$

$\cos^2\left(x\right)+\cos\left(x\right)-2$

$\left(-3.3\right)-\left(-2.4\right)$

$\int\frac{5t^2}{3t^3-2t^2-11t+10}dt$

$\log_b\left(x\right)+\log_b\left(x-4\right)=\log_b\left(21\right)$