$121-81b^2$

$\left(8-2-4\right)\left(-1\right)^2+\left(5-6\right)^2+3:\left(-3\right)\left(-6\right)-5$

$y=\frac{\left(x^2+3\right)^{\frac{2}{3}}\left(3x+2\right)^2}{\sqrt{x+1}}$

$3b^2\left(3f+4g\right)+6cf+8cg$

$\frac{1}{y}\frac{dy}{dx}=\frac{1}{1+x}$

$\int ke^{cos\left(kx\right)}sen\left(kx\right)dx$

$\frac{6x^2-10x-24}{2x-3}$