SAT Math Multiple Choice Practice Question 582: Answer and Explanation

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Question: 582

18.

Based on the chart above, which of the following could express the relationship between x and y ?

A. y = x – 4
B. y = x – 2
C. y = 2x – 1
D. y = 2x + 2
E. y = 3x – 3

Correct Answer: C

Explanation:

C Plug in the values from the chart! Use the pair (–3, –7) from the top of the chart and eliminate answers that are not true: A becomes –7 = –3 – 4, which is true. Keep it. B becomes –7 = –3 – 2, so since –7 does not equal –5, eliminate it. Keep C: –7 = 2(–3) – 1 is true. Get rid of D, which becomes –7 = 2(–3) + 2: –7 does not equal –4. Get rid of E: –7 = 3(–3) – 3. –7 does not equal –9. Now use another pair just to test A and C. Using (–1, –3), A gives –3 = –1 – 4, which is not true, so eliminate it, leaving only C. The values (–1, –3) work: –3 = 2(–1) – 1.

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