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Line k lies in the xy-plane. The x-intercept of line k is –4, and line k passes through the midpoint of the line segment whose endpoints are (2, 9) and (2, 0). What is the slope of line k ?
Give your answer as a fraction.__3/4_____
这个题先求出那条线段的中点(2,9/2)，然后斜率就是(9/2)/(2-(-4))=3/4