$5.\:\left(n+3\right)\:+\:\left(n+5\right)$

$\frac{b}{3}=2$

$20+90+518b$

$\int_2^1\left(\sqrt{x^2+1}\right)dx$

$8x^2-10x+2=0$

$\left(b+1\right)\cdot\left(b-5\right)$

$\frac{\left(-942+128x^2-31x+12x^3\right)}{\left(x+4\right)\left(x+6\right)\left(x-3\right)-\left(x-3\right)}$