4) 64 x2 dx = lim Rn, where Rn = _ f(Ck) Ax, is the Riemann sum, with Ck n-+00 k=1 n being the right endpoint. Using the formula Ck2 = n(n+1)(2n-+1) 6 , we have Rn = : i=1 A) (n+1) (n+2) 673 B) (2n+1) (n+2) 12n2 (n+1) (n+2) (n+1)(2n+1) 12n n(2n+1) 1035595 1272 (n+1)(2n+1) 6722 (n+1)(2n+1) 6723 H) n(n+2) 2n2 (n+1)(2n+1) S (n+1)(2n+1) 12n2