Question

I am trying to solve a basic function. but I get an error with my second if statement and the else.Ff you can give me a help here is the code.

(define (equation x)
  (if(> x 2) (+(-(* x x) x) 4) ) 
  (if (and (> x 1 ) (= x 1))  (and (< x 2) (= x 2)) (/ 1 x))
  (else 0)
  )

Answer 1

There are several errors in your code. And you should use a cond when dealing with multiple conditions (think of it as a series of IF/ELSE IF/…/ELSE statements).

Be aware that the expression (and (> x 1) (= x 1)) will never be true, as x is either greater than or equal to 1, both conditions can never be true at the same time. You probably meant (or (> x 1) (= x 1)), but even so that expression can be written more concisely as (>= x 1). The same considerations apply for the condition (and (< x 2) (= x 2)).

I believe this is what you were aiming for:

(define (equation x)
  (cond ((> x 2)
         (+ (- (* x x) x) 4))
        ((and (>= x 1) (<= x 2))
         (/ 1 x))
        (else 0)))