$3+2+1-4-5-7-2-3-5-6-1+2$

$\lim_{x\to1}\left(\frac{sin^20-x}{x}\right)$

$\lim_{x\to\infty}\frac{20+40x^2+x^4}{20+80x+4x^2}$

$\left(a^2x-4a^2x^2+5ax^3-x^4\right)\:\:\left(\:2x\right)\:\:$

$a^2-3ab+b^2-5ab+a^2-b^2.8ab-b^2-2a^2$

$\:\left(tanb-1\right)^2$

$\lim_{x\to0}\left(\frac{\frac{1}{x-3}-\frac{1}{3}}{x}\right)$