a Use the definition given below with right endpoints to express the area under the curve y x from 0 to 1 as a limit The area A of the region S that is bounded above by the graph of a continuous function y f x below by the x a and on the sides by the lines x a and x b is the limit of the sum of the areas of approximating rectangles f x Ax lim nia A lim R lim f x Ax f x x 11e 71 1 f x Ax lim n n1x2 b Use the following formula for the sum of cubes of the first n integers to evaluate the limit in part a 1 2 3 n n 2