Set to 0.

X

X

Now halve the coefficient of the linear term (6), square it and add it to both sides

X

factor the left side and gather terms on the right

(X + 3)

X

^{2 }+ 6X - 12 = 0X

^{2}+ 6X = 12Now halve the coefficient of the linear term (6), square it and add it to both sides

X

^{2}+ 6X + 9 = 12 + 9factor the left side and gather terms on the right

(X + 3)

^{2}= 21**(X + 3)**^{2 }**- 21 = 0**======Vertex form**(- 3, - 21)**------Vertex of the function