Question

Find the number to add to x^2-18x

to make it a perfect square trinomial. Write that trinomial as the square of a binomial.

Answer 1

add 81

Explanation:

Answer 2

A. add 81;
`(x-9)^2`

Explanation:

The perfect square formula

`(a-b)^2=a^2-2ab+b^2`

Rewrite expression
`x^2-18x` as follows:

`x^2-2\cdot 9\cdot x`

So, to form a perfect square,
`+9^2` is missed.

When we add
`9^2=81,` we will get

`x^2-2\cdot 9\cdot x+9^2=(x-9)^2`