SAT Math Multiple Choice Question 407: Answer and Explanation

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Test Information

Question: 407

x y
-1 7
0 5
1 3
2 1

2. If graphed, the ordered pairs in the table above would form a line. Where would this line intersect the x-axis?

  • A.
  • B.
  • C.
  • D. 5

Correct Answer: C

Explanation:

C

Difficulty: Medium

Category: Heart of Algebra / Linear Equations

Strategic Advice: Be careful—the 0 in the table is an x-value, which means it shows the y-intercept, not the x-intercept. You are looking for the point at which y = 0.

Getting to the Answer: You could use two of the points in the table and the slope formula to find the equation of the line, then substitute 0 for y and solve for x. However, this would use up valuable time. Instead, look for a pattern in the table. If you continue the pattern, the next ordered pair would be (3, -1), which would mean the line has dropped below the x-axis. This means the graph of the line crosses the x-axis somewhere between the x-values of 2 and 3. The only answer choice that is between 2 and 3 is (C).

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