$x^2-2x\left(n-3\right)+\left(n-3\right)^2$

$\ln\left(4x-7\right)=\ln\left(x+11\right)$

$-40\:\left(-8\right)$

$\int\frac{1}{x\left(0.4x+2\right)}dx$

$\lim_{x\to\infty}\left(e^{-x}.\ln\left(2+e^x\right)\right)$

$dy=2x\left(y+9\right)dx$

$\frac{a}{20}=\frac{a}{50}+\frac{3}{10}$