$\lim_{x\to0}\left(1-6x\right)^{-x}$

$t^{2}\frac{dy}{dt}-ty=0$

$\tan\left(x\right)-\cot\left(-x\right)=\sec\left(x\right)\csc\left(x\right)$

$100m^2-80my+16y^4$

$\frac{-2\left(ab+ac+bc\right)}{2ab+2ac+2bc}$

$f\left(x\right)=x^2\sin\left(x\right)\left(2x+1\right)^{-4}$

$8x-7+6x+8$