Digital SAT Math Test 6 Question 2

When the quadratic function $f$ is graphed in the $xy$-plane, where $y=f(x)$, its vertex $(2, -3)$ is 5 units away from the $x$-intercepts of the graph. Which equation defines $f$?
Answer:
C

Explanation

The correct answer is Choice C.

Draw the graph and locate the $x$-intercept knowing that a quadratic function is symmetrical along the vertical line that goes through the vertex of the graph.

Choice A is incorrect and may result from switching the $x$ and $y$ coordinate of the vertex.

Choice B is incorrect and may result from algebraic mistakes when finding the lead coefficient.

Choice D is incorrect and may result from sign error when writing the function in the $x$-intercept form.

✨ Expert's Tip ✨

A graph of a quadratic function is symmetric along the vertical line that goes through the vertex. Therefore, the vertex is at the middle of the two $x$-intercepts.

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