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Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

In the x y-plane, line l passes through the points (0,0)and (2,5). Line m is perpendicular to line l. What is the slope of line m?

(A) -(5/2)
(B) -(2/5)
(C) 2/5
(D) 5/2
(E) 5

答案和解析

答案：B

解析：

Line l passes through the points (0,0) and (2,5), so the slope of line l is equal to (5-0)/(2-0) = 5/2. Lines l and m are perpendicular, so the slope of line m is equal to the -reciprocal of the slope of line l. Therefore, the slope of line m is -1/(5/2) = -2/5.