Complete the square to find the vertex of the parabola?

Question

17) y=x^2 + 6x +3

19) y= -x^2 - 8x + 2

the answer to 17 is (-3, -6)

the answer to 19 is (-4, 18)

my problem is i do not know how to complete the square basically i prefer not to so if you could show me how to do these problems and explain i will be eternally grateful :]

Answer 1

x^2 + 6x +3

=x^2 + 6x +9-9+3

=(x+3)^2-6

The answer is (-3, -6)

remember y=(x-r)^2+k

V(r,k)

Do the other question in the same way

Answer 2

y= x^2 +6x + ___   +3 - ___

y=x^2 +6x +9 +3 -9  (  ___ is half the b term, squared)

y=(x+3)^2 -6 vertex is (-3, -6)

y=-x^2 -8x +2 = - (x^2 +8x + ___)    +2   + ___

y=- (x^2 +8x +16) +2 +16

y = - (x+4)^2 +18

vertex is (-4,18)