$-cos\left(-x\right)-tan\left(-x\right)sin\left(-x\right)=-sec\left(x\right)$

$\lim_{x\to3}\left(\frac{x^2}{e^x}\right)$

$a-9b+6a-4b$

$\left(x^2-4\right)\left(x^2+6x+9\right)$

$\log_{10}\left(x^2+15\right)=\log_{10}\left(x+3\right)+\log_{10}\left(x\right)$

$\frac{dy}{dx}=\frac{xe^y}{2t-1}$

$\int\left(2x\:+\:1\right)\:\left(x\:-\:9\:\right)^{\frac{1}{2}}dx$