Find the value V of the Riemann sum V = n ∑ k = 1 f ( c k ) Δ x k V=∑k=1nf(ck)Δxk for the function f ( x ) = x 2 + 4 f(x)=x2+4 using the partition P = { 1, 2, 4, 7 }, where the c k ck are the left endpoints of the partition. V =