$\left(7y^2-1\right)\left(7y^2+2\right)$

$\left(8-11-5\right)-\left(12-13\right)-\left(11-4\right)$

$\left(\frac{1}{\sin\left(x\right)}\right)-\left(\frac{1}{\cos x}\right)=\left(\frac{\cos x-\sin x}{\sin x\cos x}\right)$

$\frac{3x-4}{3-x}=2$

$\sin\left(4t\right)=4\text{sent}\cos t\left(1-2\sin^2t\right)$

$\lim_{x\to1}\left(\frac{x^7-1}{x^8-1}\right)$

$\lim_{x\to\infty}\left(\frac{e^x}{x^2-x}\right)$