Which equation is y=9x^2+9x-1 rewritten in vertex form?

Hello:

y = 9x²+9x-1

y = 9 (x²+x) - 1

y = 9 (x²+2 (1/2) x + (1/2) ² - (1/2) ²) - 1

y = 9 ((x+1/2 x) ² - 1/4) - 1

y = 9 (x+0.5) ² - 9/4 - 1

y = 9 (x+0.5) ²-13/4 ... (vertex form)