SAT Math Multiple Choice Practice Question 590: Answer and Explanation

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Question: 590

4. Which of the following is the graph of a line perpendicular to the line defined by the equation 2x + 5y = 10 ?


Correct Answer: E


E Convert the equation into the y = mx + b format: 5y = –2x + 10. Simplified, this is . The slope in this equation is ?. A line that is perpendicular will have a slope that is the negative reciprocal of this, or . Right away you can eliminate B and C because their slopes are negative. Use points in the graph to find the slope of each answer. Eliminate A; it has points at (1, 0) and (2, 5), for a slope of 5—too steep. Eliminate D, because its points, (1, 0) and (6, 2), give a slope of , the reciprocal of what we want. E is correct; its points, (1, 0) and (3, 5), give a slope of .

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