The principal solutions of $$\sqrt{3} \sec x+2=0$$ are

$$\int \operatorname{cosec}(x-a) \operatorname{cosec} x d x=$$

If $$f(x)=2x^3-15x^2-144x-7$$, then $$f(x)$$ is strictly decreasing in

The equation of the plane that contains the line of intersection of the planes. $$x+2 y+3 z-4=0$$ and $$2 x+y-z+5=0$$ and is perpendicular to the plane $$5 x+3 y-6 z+8=0$$ is