$2x\frac{dy}{dx}-4x^2=0$

$tx'=xlnx$

$ln\left(2x+1\right)+ln\left(x-3\right)-2ln\left(x\right)$

$a^2+2x+1=0$

$\left(1+\sin\left(\infty\right)\right)\cdot\left(1-\sin\left(\infty\right)\right)=\cos\left(\infty\right)^2$

$\cos\left(2x\right)=\frac{1}{\sqrt{2}}$

$\lim_{x\to0}\left(\frac{sen\:x\:+\:sen\:y}{x\:+\:y}\right)$