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The vertex of a parabola is at (12,-4) and its axis of symmetry is vertical. One of the x-intercepts is at (18,0). What is the x-coordinate of the other x-intercept?

 Nov 24, 2022
 #1
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You can use vertex form a(x - h)^2 + k, so that the vertex of the parabola is at (h, k) = (12, -4).

a(x - 12)^2 - 4 = y

Plug in 18

a(18 - 12)^2 - 4 = 0

36a = 4

a = 1/9

(x - 12)^2 - 36 = 9y

If y = 0

x - 12 = +-6

The other x - intercept is (6, 0)

 Nov 24, 2022

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