$a-9\cdot a+12$

$\int\frac{\sqrt{9-x^2}}{3x^2}dx$

$\int_1^{\infty}\left(\frac{-6x^2-3}{\left(x^3+x\right)^3}\right)dx$

$9,375-8,125$

$\int_{-7}^{-\frac{77}{12}}\frac{x+2}{x\cdot\left(x+1\right)^2}dx$

$-2+2+-1+8$

$8\:arc\:cot\:\left(\sqrt{\frac{\left(16-x^2\right)}{x}}\right)$