Q.Find the area of the region included between: $y = x^2$ and the line $y = 4x$

When two curves $y = f(x)$ and $y = g(x)$ cross each other, they enclose a bounded region between them. To find its area, the first step is always to locate the points where the two curves meet, by solving their equations simultaneously -- these intersection points become the limits of integration, and they are almost never given directly in the problem statement. …