Notice that the bounds are reverse. What does that 'do' to the way we evaluate area?
Two shifts happen to the integrand: It is shifted two units up. It is shifted two units right. The bounds also changed.
units is like adding the integral:
In other words, it's like adding a rectangle with height
and base .
Shifting an integral to the right could make it impossible to evaluate.
Fortunately, in this case, the bounds also shifted
units to the right.