Line A is perpendicular to line B. If the slope of line A is multiplied by 4, what must the slope of line B be multiplied by in order for the lines to still be perpendicular?

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Accepted Answer

The slopes of perpendicular lines are negative reciprocals of each other. Therefore, if the slope of line A is m, the slope of line B is – 1 ⁄ m . If the slope of line A is multiplied by 4, it becomes 4m. The negative reciprocal of 4m is – 1 ⁄ 4m . To change the original slope of line B, – 1 ⁄ m , to this new slope, – 1 ⁄ 4m , you must multiply by 1 ⁄ 4 .

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