==> (define (sum term a next b)
(if (> a b) 0
(+ (term a)
(sum term (next a) next b))))
SUM
==> (define (cube x) (* x x x))
CUBE
==> (define (square x) (* x x))
SQUARE
==> (define (1+ x) (+ x 1))
1+
==> (sum cube 1 1+ 10)
3025
==> (sum square 1 1+ 10)
385