`f(x)` is a continuous and bijective function on `Rdot` If `AAt in R ,` then the area bounded by `y=f(x),x=a-t ,x=a ,` and the x-axis is equal to the area bounded by `y=f(x),x=a+t ,x=a ,` and the x-axis. Then prove that `int_(-lambda)^lambdaf^(-1)(x)dx=2alambda(gi v e nt h a tf(a)=0)dot`