$\lim_{x\to-\infty}\left(x^{-3}e^x\right)$

$\log\left(x^2-1\right)-\log\left(x+1\right)=2$

$3\cot^2\left(x\right)-4\csc\left(x\right)=1$

$x^4+16x^2y^2+64y^4$

$10\:x\:\left(-4\right)\:+\:5\:x\:\left(-4\right)$

$f\left(x\right)=\frac{x^2-25}{x^4-125x}$

$\lim_{x\to+\infty}\left(\left(\frac{2^x+4^x}{3}\right)^{\frac{1}{x}}\right)$