Question

In the function f(x) = 4(x2 − 6x + ____) + 20, what number belongs in the blank to complete the square?

Answer 1

Take half of the x-term coefficient and square it.

Answer 2

The x-term coefficient is -6.
Take half of -6, and square it.
What do you get?

Answer 3

Half of it so like -3?

Answer 4

Yes. Now square it.

Answer 5

ok its -1.73

Answer 6

or well - 1.7

Answer 7

Not square root. Square it.

\((-3)^2 = (-3)(-3) = 9\)

Answer 8

Oh square it XD

Answer 9

\(\sqrt 3 \approx 1.732\) <----- not this

\((-3)^2 = 9\) <---- this is what you do

Answer 10

Ok understood!

Answer 11

The answer is 9.
Just so you know, this method (take half of the x-term coefficient and square it) works for completing the square, but it only works when the coefficient of the x^2 term is 1. In your case, you do have x^2 - 6x, so you see that the coefficient of the x^2 term is 1.

Answer 12

Thanks

Answer 13

You're welcome.