A function f : R $$\to$$ R is defined as f(x) = x³ + 1. Then the function has

If $$\sin y = x\cos (a + y)$$, then $${{dx} \over {dy}}$$ is

The points on the curve $${{{x^2}} \over 9} + {{{y^2}} \over {25}} = 1$$, where tangent is parallel to x-axis are

Three points P(2x, x + 3), Q(0, x) and R(x + 3, x + 6) are collinear, then x is equal to