Calculus help please meaning of the value of the integral

Question

 Use a graph of the function to explain the geometric meaning of the value of the integral.

Answer 1

The usual 'basic' explanation is that the definite integral of a function, from lower bound a to upper bound b, is the area under the curve--at least when the function being integrated is non-negative and continuous on [a,b]. (Area between curve & x-axis, over [a,b]).