$6\left(x-3\right)=42$

$\lim_{x\to1}\frac{x^2-ax+a-1}{\left(x-1\right)^2}$

$\frac{\left(3y^3\right)\left(2y^2\right)^2}{\left(y^4\right)^3}.\left(y^3\right)$

$\int\left(\cos\left(xy\right)\right)dy$

$x^2-13x+84.5$

$\left(2a^2-a^3\right)^3$

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