$$y=\tan\left(x^2-x\right)$$

$$20x^2+23x-21$$

$$\left(3a^2b+5ab^2\right)^2$$

$$\left(7a^2+5x^3\right)\:\left(7a^2+6x^2\right)$$

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

$$1^3\cdot6^2$$

$$\frac{1}{100}r^2+\frac{1}{5}rt+t^2$$