Haskell - Passing a function as an argument - function

Question

so in haskell I have the following 2 functions made (they are just performing some math operations)
cubicQ :: Float -> Float -> Float -> Float
cubicQ a b c = (3*a*c - b**2) / (9*a**2)
cubicR :: Float -> Float -> Float -> Float -> Float
cubicR a b c d = (9*a*b*c - 27*(a**2)*d-2*b**3)
I am to make a third function cubicS that has a requirement that the function be of type Float -> Float -> Float and it calculates its output from q and r, which is the output for cubicQ and cubicR. How would I pass the functions cubicQ and cubicR as arguments q and r in cubicS? Below is what I have tried so far but I am stumped. Any help would be greatly appreciated.
cubicS q r = (r+ (q**3+r**2)**(1/2))**(1/3)
where q = (cubicQ a b c d)
r = (cubicR a b c)

Answer 1

try this:
cubicQ a b c = (3*a*c - b**2) / (9*a**2)
cubicR a b c d = (9*a*b*c - 27*(a**2)*d-2*b**3)
cubicS q r = (r+ (q**3+r**2)**(1/2))**(1/3)
f a b c d = cubicS (cubicQ a b c) (cubicR a b c d)
main = do print $ f 1 2 3 4
or:
cubicS a b c d = (r+ (q**3+r**2)**(1/2))**(1/3)
where q = cubicQ a b c
r = cubicR a b c d
or:
cubicS a b c d =
let q = cubicQ a b c
r = cubicR a b c d
in (r+ (q**3+r**2)**(1/2))**(1/3)
see:
cubicQ :: Float -> Float -> Float -> Float
cubicQ a b c = (3*a*c - b**2) / (9*a**2)
cubicR :: Float -> Float -> Float -> Float -> Float
cubicR a b c d = (9*a*b*c - 27*(a**2)*d-2*b**3)
cubicS :: Float -> Float -> Float -> Float -> Float
cubicS a b c d =
let q = cubicQ a b c
r = cubicR a b c d
in
(r+ (q**3+r**2)**(1/2))**(1/3)
main = do print $ cubicS 1.1 2.2 3.3 4.4
output:
9.736999e-2
and if you restricted to cubicS being cubicS: Float -> Float -> Float:
cubicQ a b c = (3*a*c - b**2) / (9*a**2)
cubicR a b c d = (9*a*b*c - 27*(a**2)*d-2*b**3)
cubicS q r = (r+ (q**3+r**2)**(1/2))**(1/3)
cureS a b c d = cubicS q r
where q = cubicQ a b c
r = cubicR a b c d
main = do print $ cureS 1.1 2.2 3.3 4.4