$\lim_{x\to0}\left(\frac{ln\left(\cos\left(x\right)\right)}{87x^2}\right)$

$4bf^7\cdot\left(2b+9\right)$

$\frac{dy}{dx}=y=\left(x+2\right)^2\sqrt{x^2+2}$

$\frac{sin^2\left(x\right)}{sin^2\left(x\right)+cos^2\left(x\right)}$

$\sin\left(90-\theta\right)$

$6x+2y$

$15y+6x-8-8y-3x$