Advanced Math practice question

Answer: 20

The vertex is at x = 4, where y = 16 − 32 + c = c − 16. On y = x, this equals 4: c − 16 = 4, so c = 20.

Common wrong answers

If you answered 4

4 is the vertex's x-coordinate, not c.

If you answered 12

12 comes from c − 16 = −4, a sign slip.

If you answered 16

16 puts the vertex on the x-axis (y = 0), not on y = x.

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