$$\frac{10a^2b^3c^4+20a^3b^2c^2+25a^2b^4c^3}{5abc}$$

$$\frac{cos2x+sin2x}{1+tan2x}$$

$$2x^2+6x-x-3$$

$$\int\frac{3x^3+5}{x^2-x-2}dx$$

$$\cot\left(x\right)^2\sec\left(-x\right)^2$$

$$20n+45$$

$$25cos^2\left(x\right)-9=0$$