SICP Exercise 1.40

Question

Define a procedure cubic that can be used together with the newtons-method procedure in expressions of the form

copy(newtons-method (cubic a b c) 1)

to approximate zeros of the cubic $x^3+a{x}^2+bx+c$.

Answer

copy(define (cubic a b c)
  (λ (x) (+ (cube x) (* a (square x)) (* b x) c)))