$\frac{48}{6}$

$\lim_{x\to1}\left(\frac{\sqrt{x^2+15x+4}}{x-1}\right)$

$12u=24+6u$

$\lim_{x\to2}\left(\frac{3x+1}{x^2-4}\right)$

$\int\frac{\left(2x^2+5x+1\right)}{\left(x-1\right)\left(x+3\right)^2}dx$

$\left(2x-1\right)\left(x+2\right)\left(4x-3\right)$

$-11+4\left(b+2c\right)-5-7b$