a) use definition 2 to find an expression for the area under the curve y=x^3 from 0 to 1 as a limit.(b) the following formula for the sum of the cubes of the first n integers is proved in Appendix E. useit to evaluate the limit in part (a).1^3 + 2^3 +3^3+.....n^3 = [n(n+1)/2]^2Definition 2: The area A of the region S that lies under the graph of the continuous function f is the limit of the sum of the areas of approximating.