Vertex form flips the sign of h: the SAT math trap

Short answer: Form is a(x − h)² + k. Plus inside the parentheses means h is negative.

The trap, in one question

Tempting answer: (3, −5)

Correct answer: (−3, −5)  (x + 3 = x − (−3))

How to spot it in 3 seconds

Form is a(x − h)² + k. Plus inside the parentheses means h is negative.

FAQ

What is the vertex form flips the sign of h trap on the SAT?

Example: What is the vertex of the graph of y = 2(x + 3)2 − 5? The tempting answer is (3, −5); the correct answer is (−3, −5) (x + 3 = x − (−3)).

How do you avoid the vertex form flips the sign of h trap?

Form is a(x − h)² + k. Plus inside the parentheses means h is negative.

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