Let f (x) = x. Find a constant m such that
Here's the graph of f (x) = x on [-2,4]:
From this graph we can see that
m(4-(-2)) = 6.
Since (4-(-2)) = 6, We must have m = 1. The weighted area between f (x) = x and the x-axis on [-2,4] is the same as the weighted area between m = 1 and the x-axis on [-2,4].