Advanced Math practice question

Answer: 1

Set equal: x² + c = 2x, so x² − 2x + c = 0. Exactly one solution means the discriminant is 0: (−2)² − 4(1)(c) = 4 − 4c = 0, so c = 1. (The point of contact is (1, 2).)

Common wrong answers

If you answered 0

With c = 0, x² = 2x has TWO solutions, x = 0 and x = 2.

If you answered 2

2 is the slope of the line, not c.

If you answered 4

4 is the discriminant's first term (b² = 4); the condition 4 − 4c = 0 gives c = 1.

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