1.40 Exercise 1.40

We want cubic to be a procedure of three parameter a, b, and c that returns a procedure of one parameter x that evaluates the function x^3 + ax^2 + bx + c. This can be done as so:

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

We can verify this works with an example, finding the root of the function x^3 + 2x^2 + 3x - 5 (which is approximately 0.89456):

> (newtons-method (cubic 2 3 -5) 1.0)
0.8945582482428005

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1	Chapter 1
2	Chapter 2
3	Chapter 3
4	Chapter 4
5	Chapter 5

1.1	Exercise 1.1
1.2	Exercise 1.2
1.3	Exercise 1.3
1.4	Exercise 1.4
1.5	Exercise 1.5
1.6	Exercise 1.6
1.7	Exercise 1.7
1.8	Exercise 1.8
1.9	Exercise 1.9
1.10	Exercise 1.10
1.11	Exercise 1.11
1.12	Exercise 1.12
1.13	Exercise 1.13
1.14	Exercise 1.14
1.15	Exercise 1.15
1.16	Exercise 1.16
1.17	Exercise 1.17
1.18	Exercise 1.18
1.19	Exercise 1.19
1.20	Exercise 1.20
1.21	Exercise 1.21
1.22	Exercise 1.22
1.23	Exercise 1.23
1.24	Exercise 1.24
1.25	Exercise 1.25
1.26	Exercise 1.26
1.27	Exercise 1.27
1.28	Exercise 1.28
1.29	Exercise 1.29
1.30	Exercise 1.30
1.31	Exercise 1.31
1.32	Exercise 1.32
1.33	Exercise 1.33
1.34	Exercise 1.34
1.35	Exercise 1.35
1.36	Exercise 1.36
1.37	Exercise 1.37
1.38	Exercise 1.38
1.39	Exercise 1.39
1.40	Exercise 1.40
1.41	Exercise 1.41
1.42	Exercise 1.42
1.43	Exercise 1.43
1.44	Exercise 1.44
1.45	Exercise 1.45
1.46	Exercise 1.46