$\sin\left(8x\right)\sin\left(9x\right)+\cos\left(8x\right)\cos\left(9x\right)$

$-1>3+\frac{k}{8}$

$\int\frac{5x+10}{\left(x-2\right)\left(x-5\right)}dx$

$3lnydy\:=\:xe^xdx$

$-3x^{-7}y^{-6}7x^{11}y^{-5}$

$x-4\ge5x+20$

$\ln\left(x\right)-\left[\ln\left(x+1\right)+\ln\left(x-1\right)\right]$