$\left(+21\right)\:-\left(-35\right)$

$\left[\left(-4\right)x\left(-2\right)\right]x\left(6\right)$

$\frac{x^5-3x^3-6}{x-1}$

$\left(10x\right)\frac{x+2}{3}=\left(10x\right)\frac{3x-2}{6}$

$\left(2x-7\right)^2-4\left(x-3\right)\left(x+3\right)$

$3\log\left(6\right)+3\log\left(x\right)$

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