Using Trapezoidal rule with one interval, the approximate value of the definite integral: ∫12 dx/(1+x2) = _______ (rounded off to 2 decimal places).

Given y = epxsin(qx), where p and q are non-zero real numbers, the value of the differential expression d2y/dx2 - 2p(dy/dx) + (p2+q2)y is

The volume of the solid formed by a complete rotation of the shaded portion of the circle of radius R about the y-axis is kπR3. The value of k is: