$6+7x=69$

$10y^2-19xy+7x^2+12xy$

$y=\frac{\left(3x^2+1\right)^4\sqrt{3-2x}}{\left(x+4\right)^2}$

$\frac{\csc\left(x\right)+1}{\csc\left(x\right)+5}=\frac{1+\sin\left(x\right)}{1+5\sin\left(x\right)}$

$3\left(x+1\right)\left(x-4\right)$

$4i^2-5i-2$