The steps in writing f(x) = 18x + 3x2 in vertex form are shown, but a value is missing in the last step.
write the function in standard form.
f(x) = 3x2 + 18x
factor a out of the first two terms. f(x) = 3(x2 + 6x)
form a perfect square trinomial.
f(x) = 3(x2 + 6x + 9) – 3(9)
write the trinomial as a binomial squared. f(x) = 3(x + – 27
what is the missing value in the last step?

3

Step-by-step explanation:

f(x) = 18x + 3x^2

f(x) =  3x^2+18x

Factor out a 3

     = 3(x^2 +6x)

Take the coefficient of x, divide by 2 and then square

6/2 = 3 3^2 =9

Remember the 3 out side 3*9 =27 so we are really adding 27

3(x^2+6x+9) -3*9

The number inside the parentheses added to x is b/2  or 6/2

3(x+3)^2 -27

Step-by-step explanation:

In the last step is missing the number 3 which is the second term of the binomial squared expression.

Basically, the complete step is

As you can see, the three inside the parenthesis is the missing part in the last step.

the circle one