The interval in which the function $$f(x)=2 x^3+9 x^2 +12 x-1$$ is decreasing is :

$$\int \frac{\sec x}{\sec x-\tan x} d x$$ equals:

$$\int_\limits{-1}^1 \frac{|x-2|}{x-2} d x, x \neq 2 \text { is equal to: }$$

The sum of the order and the degree of the differential equation $$\frac{d}{d x}\left(\left(\frac{d y}{d x}\right)^3\right)$$ is: