$3.12-1.79$

$\int\left(2x+1\right)\sin\left(7x\right)dx$

$\frac{d}{dx}\left(\frac{x^2}{x^2+y^2+z^2}\right)$

$\int\left(x^2\cdot x\sqrt{x^2+1}\right)$

$a^2b-3ab^2-ab^2+a^2b+5a^2b^2$

$-\cos\left(x\right)=\sin\left(x-\frac{\pi}{2}\right)$