Math;Factoring.?

To complete the square first you need to factor (only numbers) so you get 5(x^2+3x) The next thing to do is to divide the three in half= 1.5 and square it so you now get 5(x^2+3x+2.25) Now since you added 11.25 [b/c (5)(2.25)] what you do to one side you have to do to the other so you subtract 7.5. Your final answer is 5(x^2+3x+1.5)-11.25 To make it a perfect square you would now change it to 5(x+1.5)^2-11.25. your coordinates are (-1.5,-11.25) To get -1.5 you look at 1.5 and ask what plus 1.5 will give you 0 therefore you get -1.5