We'll put y in function of x:

Look the graph of the function in the attached figure. The areas above and below the x-axis are equal. So, we can represent the area bounded by the graph as:

Using that to calculate the area bounded is equal to calculate the double of area above the x-axis.
The line x=z divides the region into two regions of equal area with 0 ≤ x ≤ 2, then:

