Question

In the function f(x)= 4 ( x²- 6x +___ ) +20 , what number belongs in the blank?

Answer 1

If the brackets need to be a square term of the form (x+h)^2
then
just half the co-efficient of x term and square it.

So here it will be
(-6)/2 = -3
squaring it, (-3)^2 = 9

so 9 is what goes in the blank to make the bracket () of the form (x+h)^2