Use the completing the square method to find the vertex form if the quadratic function y=2x^2+8x+18.?

Answer 1

y=2x^2+8x+18. First factor out your 2.
y=2(x^2+4x+9). Then complete the square.
y=2(x^2+4x+4+9-4). Then remove unnecessary elements (The 9 and -4.
y=2(x^2+4x+4)+10. Factor the trinomial.
y=2(x+2)^2+10
And, viola!

Answer 2

First factor out 2, giving you y=2(x^2+4x+9).
Now, (4/2)^2=4.
So, knowing this y=2(x^2+4x+4+5).
Or y=2(x^2+4x+4)+(2*5).
So, we need to subtract 2*5=10 from both sides, giving us
y-10=2(x^2+4x+4), or y-10=2(x+2)^2.