$3\left(x+y\right)-6\left(x+y\right)$

$\lim_{x\to\infty}\frac{1+7^n}{4^n}$

$\left(9w\right)^2$

$\frac{dy}{dx}\left(\sec^2\left(x\right)+\csc^2\left(y\right)=4\right)$

$\int\frac{1}{16-9\cdot x^2}dx$

$w^2=64$

$\frac{tan\left(x\right)+cot\left(y\right)}{\frac{tan\left(x\right)}{tan\left(y\right)}}=tan\left(y\right)+cot\left(x\right)$