Make a sketch of the region{(x,y): 0 ≤ y ≤ x2 + 3; 0 ≤ y ≤ 2x + 3; 0 ≤ x ≤ 3} and find its area using integration.
To find area given equations are
Y = x2 + 3 …(i)
Y = 2x + 3 …(ii)
And x = 3 …(iii)
Solving the above three equations to get the intersection points,
x2 + 3 = 2x + 3
Or x2 – 2x = 0
Or x(x – 2) = 0
And x = 0 or x = 2
∴ y = 3 or y = 7
Equation (1) represents a parabola with vertex (3, 0) and axis as y – axis.
Equation (2) represents a line a passing through (0, 3) and ( – 3/2, 0)
The points of intersection are A (0,3) and B(2,7).
These are shown in the graph below:
Required area =
The area of the region{(x,y): 0≤y≤x2 + 3; 0 ≤ y ≤ 2x + 3; 0 ≤ x ≤ 3} is