$\left(a+1\right)\left(a-1\right)+\left(a+1\right)^2$

$\lim_{x\to0}\left(\frac{sin\left(x\right)}{in\left(x+1\right)\cdot cos\left(x\right)}\right)$

$sec\:\left(x\right)=0$

$x\frac{dx}{dy}=-y\:=x^2$

$\left(-20.16\right)\:\left(-29\right)$

$5\sqrt{x^2+3-1}$

$\left(2.8\right)\cdot\left(-30.6\right)$