$$18x^9-21x^{10}-54x^{11}$$

$$\left(-3x^3y^2\right)\left(5xy^{-1}\right)$$

$$1-\left(\frac{sin^2x}{1+cosx}\right)=cosx$$

$$8^{-5}\cdot8^6$$

$$\int\frac{1}{p\sqrt{7-p^2}}dp$$

$$-4ab+7a^2b+2a^2b^2$$

$$x^2-5x+25=4$$