Complete the square. Write the resulting perfect square trinomial as the square of a binomial. X2+9x

Answer 1

x^2 + 9x

= x^2 + 9x + 81/4 - 81/4 , take 1/2 of the coefficient of the x term, square it, then add and subtract it
= (x + 9/2)^2 - 81/4