Question

How do you factor `x^2+18x+81`?

Answer 1

`x^2+18x+81=(x+9)^2`

Explanation:

As `81` is the square of `9` and middle term `18` is double of this number, (compare it with `(x+a)^2=x^2+2ax+a^2`)

Hence `x^2+18x+81` is a complete square.

`x^2+18x+81`

= `x^2+2xx9xx x+9^2`

= `(x+9)^2`