Question 1199993
(3x-a)^2 = 9x^2 - 6ax -> 6a = 15 -> a = 5/2
(3x - 5/2)^2 = 9x^2 - 15x + 25/4.
The constant term in the original equation is zero so we must subtract 25/4.
Ans: (3x - 5/2)^2 - 25/4