$$6.5=6.4-\log\left(x\right)$$

$$xy^{-2}\cdot x^{-1}y^{-2}$$

$$\frac{6}{3}+\frac{\left(-5\right)}{3}+\frac{2}{3}$$

$$3x^2-5x+4>0$$

$$7a^3\left(6a^2+a\right)^2-4a^6$$

$$4x-16=3x-14$$

$$\int x\ln\left(\frac{39-x}{42+x}\right)dx$$