Question 269463
To complete the square rewrite the equation as
(i) {{{p^2 + 3p + _____ = 9 + ______}}}
step 1 - take 1/2 of the middle term and square it to get
(ii) {{{p^2 + 3p + (3/2)^2 = 9 + (3/2)^2}}}
notice the blanks were used to put the 1/2 term squared. 
step 2 - rewrite the left side as a binomial squared and simplify the right side to get
(iii) {{{(p + 3/2)^2 = 45/4}}}
step 3 - take a square root to get
(iv) {{{p + 3/2 = +-sqrt(45)/2}}}
step 4 - subtract 3/2 to get
(v) {{{p = (-3 +-sqrt(45))/2}}}