SOLUTION: The value of c for which the vertex of the parabola y=x^2+6x+c will lie on the x-axis is _____?

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Question 634613: The value of c for which the vertex of the parabola y=x^2+6x+c will lie on the x-axis is _____?
Found 2 solutions by richwmiller, ewatrrr:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
y=x^2+6x+9
or
y=(x+3)^2

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

y=x^2+6x+c

The value of c for which the vertex of the parabola will lie on the x-axis

y = (x - 3)^2 - 9  + c   |comleting the Square to put into Vertex form for:  V(-3,0)

the vertex form of a Parabola opening up(a>0) or down(a<0), y=a%28x-h%29%5E2+%2Bk 

where(h,k) is the vertex

  c = 9    and y+=+%28x-3%29%5E2