Add the proper constant to each binomial so that the resulting trinomial is a perfect square trinomial. Then factor the trinomial: x^2-18x+____?
Take the second term of the equation and divide it to two. Then, take the square of the quotient. In this problem, the middle term is -18. (-18/2)² = 81 The perfect square equation would be x² - 18x + 81. The factors would be (x - 9)²