$7a\left(x+y+1\right)-3b\left(x+y+1\right)$

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

$\left(x+11\right)\left(x+4\right)$

$x^2\sqrt{3^2}$

$\lim_{x\to\infty}\left(x\left(e^{\frac{1}{x}}-x\right)\right)$

$\lim_{x\to0}\left(\frac{x^2}{\sqrt{16-x^2}-4}\right)$

$\lim_{x\to\infty}\left(1-\frac{2}{3x}\right)^{x^2}$