I have got help from Damon on this question but all I need is help on integrating the answer he gave me into my original equation:

Question

y=-15/20.25(x+1.5)^2+0

Here's Damon's help: (x+1.5)(x+1.5) = x^2 + 1.5 x + 1.5 x + (1.5*1.5)

= x^2 + 3 x + 2.25

So would I put this into my original quadratic equation?

Please and thank you as the help would be much appreciated!