For the function f and interval a,b, use the given approximation method to approximate the signed area between the graph off and the x-axis on[a,b]. Determine whether your approximationis likely tobean over-approximation oran under-approximation of the actual area. (Round your answers to three decimal places.)f(x)=7-4x,[a,b]=[-2,2],n=3(a) left sum = This isan over-approximation.This isan under-approximation.(b) right sum = This isan over-approximation.This isan under-approximation.