(b) The graph of y = x − 3 is the line with slope shown in the bottom figure. We compute the integral as the difference of the areas of the two triangles:10(x − 3) dx0 = A1 − A2 = − 4.5 = .

EXAMPLE 4 Evaluate the following integrals by interpreting each in terms of areas.(a)    39 − x2 dx0(b)    10(x − 3) dx0SOLUTION (a) Since f(x) = 9 − x2 ≥ 0, we can interpret this integral as the area under the curve y = 9 − x2 from 0 to . But since y2 = , we get x2 + y2 = 9, which shows that the graph of f is a quarter-circle with radius in the top figure. Therefore,39 − x2 dx0 = 14𝜋(3)2 = .(b) The graph of y = x − 3 is the line with slope shown in the bottom figure. We compute the integral as the difference of the areas of the two triangles:10(x − 3) dx0 = A1 − A2 = − 4.5 = .

The graph of f is shown. Evaluate each integral by interpreting it in terms of areas.(a)    10f(x) dx0 (b)    25f(x) dx0 (c)    35f(x) dx25 (d)    45f(x) dx0

Find the area enclosed by the curves y = x3 + x and y = 3x2 − x.

The area enclosed by the lines x = 0, x = 2, y = x and y = 3 is

Find the exact area of the region bounded by the graphs with equations:y = x + 3 and y = 12 + x − x2