$\frac{d^4}{dx^4}senx+cosx$

$\frac{dy}{dx}=1+cos\left(y\right)$

$\log_{12}\left(x+1\right)=1-\log_{12}\left(x-3\right)$

$5a-\left\{3b-\left[a-2\left(a-b\right)\right]\right\}$

$\lim_{x\to\infty}\left(e^{-x}\right)\left(x^3-9x^2+22\right)$

$\frac{dy}{dx}=\frac{e^{5x+y}}{xy}$

$x^2-7-x^2+4x-1$