$-2\cdot18$

$\lim_{x\to1}\left(\frac{x^4+6x^2-7}{x^4+8x^2-9}\right)$

$\frac{-2x^3+2x^2-4x+1}{2x^2+2x+2}$

$\lim_{x\to1}\left(\frac{x^2-5x+4}{x^3-1}\right)$

$2x^2-30x+180$

$4\log\sqrt{a}$

$\cosh\left(x-y\right)=\cosh\left(x\right)\cosh\left(y\right)-\sinh\left(x\right)\sinh\left(y\right)$