SOLUTION: find the number b such that the vertex of the parabola y= x²+bx +c lies on y-axis

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Question 1106914: find the number b such that the vertex of the parabola y= x²+bx +c lies on y-axis
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Converting to vertex form,
y=%28x%5E2%2Bbx%2B%28b%2F2%29%5E2%29%2Bc-%28b%2F2%29%5E2
y=%28x%2Bb%2F2%29%5E2%2Bc-%28b%2F2%29%5E2
So the vertex would lie on the x axis at x=-b%2F2 and the y value would be equal to zero,
0=%28-b%2F2%2Bb%2F2%29%5E2%2Bc-%28b%2F2%29%5E2
c=%28b%2F2%29%5E2