3) Given interval f ( x )=x 2 +3 , find the exact area [ 1,3 ] A of the region under y=f ( x ) on the by first computing the sum n f ( xk ) x k=1 n and then taking the limit as n . Hint: k 2= k=1 n ( n+1 )( 2 n+1 ) 6 (3) _____ (Note: If limits are not used correctly, the maximum number of points possible for this problem will be 5 points out of 20 points.) ( A ) 14 (B ) 44 3 ( C ) 13 ( D) 56 3 of the above (E ) of the above (E )