$\left(a+b\right)^2-\left(b-a\right)^2+\left(a-b\right)^2-a^2-4b^2$

$2x^2-8x=-30$

$3+\left\{4-8-\left[5-\left(-8+2-7+5\right)-6\right]+\left(-9-7\right)+8\right\}$

$\left(1+2a\right)^3$

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

$\int e^x\cdot3\cos\left(2x\right)dx$

$\int a^{3x}dx$