## anonymous one year ago Which point is the vertex of the parabola? a: (-2, -3) b: (2, 3) c: (-2, 3) d: (2, -3)

1. SolomonZelman

It all depends on the parabola....

2. anonymous

thats all they gave me

3. anonymous

well they gave me this too

4. SolomonZelman

what this?

5. anonymous

y = x2 + 4x + 1

6. SolomonZelman

oh, that is much better!

7. SolomonZelman

y=x²+4x+1 you have to complete the square in this case.

8. SolomonZelman

Let me ask you this, if you had $$\large\color{black}{ \displaystyle y=x^2+4x+\text{___} }$$ then what number would you want in place of a blank to make this trinomial/expression a perfect square?

9. anonymous

1

10. SolomonZelman

no, you wouldn't want a "1"..... you need this expression to factor into two equal parts.

11. SolomonZelman

well (x+2)(x+2) would give you the first term x² and second term 4x and a third term 4, is this right or not?

12. anonymous

right