Find the area of the region in the xy-plane bounded above by the graph of the function f(x)=4, below by the x-axis, on the left by the line x=4, and on the right by the line x=24
The area is just a rectangle with a length of 20 (x=24-4=20) and a height of 4:
Area = L*H = 20*4 = 80
In calculus, to find the area under f(x)=4 between x=4 and x=24, take the integral of f(x) from x=4 to x=24
24 24 24 24
Area = ∫f(x) dx = ∫4 dx = 4∫ dx = 4x| = 4(24) - 4(4) = 96 - 16 = 80
4 4 4 4
