Question

Which equation, when graphed, has x-intercepts at (2, 0) and (4, 0) and a y-intercept of (0, –16)?

f(x) = –(x – 2)(x – 4)
f(x) = –(x + 2)(x + 4)
f(x) = –2(x – 2)(x – 4)
f(x) = –2(x + 2)(x + 4)

Answer 1

f(x) = –2(x – 2)(x – 4)

Explanation:

In the first two possible answer choices we have a 2 and a 4, whose product is 8, whereas we need a y-intercept of -16. So omit the first two choices.

If the x-intercepts are at (2, 0) and (4, 0), the corresponding factors must be (x - 2)(x - 4), so the third answer, f(x) = –2(x – 2)(x – 4), must be the correct one.

Answer 2

Number 3 is the correct answer

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