$\frac{1-cos\left(2x\right)}{2-2sin\left(2x\right)}=y^2$

$\lim_{x\to0}\left(\frac{12sinx}{x}\right)$

$\frac{d^4}{dx^4}\left(x^4-4x^2\right)$

$36x^2-19x-42$

$9x^3-7xy^2-4x^3-5x^3+5xy^2$

$\frac{d}{dx}\left(4y-8x^3=20\right)$

$\lim_{x\to0}\left(\ln\left(3x\right)-\ln\left(\sin\left(x\right)\right)\right)$