$\frac{1}{16tan^2x\sqrt{16+16tan^2x}},\:x=4tanx$

$4\le4f-4$

$\left(15-7\right)+\left(6-1\right)-\left(9-6\right)+\left(12-9\right)$

$3yz^2\cdot5y^2z$

$\left(4x^3-6y^2\right)^3$

$2\log_a\left(x\right)-\log_a\left(y\right)$

$\frac{d^2}{dx^2}\left(\frac{\left(\cos\:\left(5x^4\right)-1\right)}{x^7}\right)$