Find the slope of line AB that is perpendicular to the line EF whose

Question

Find the slope of line AB that is perpendicular to the line EF whose equation is 4y + 12x = 48.

(A) 2/3
(B) 1/3
(C) 3
(D) -3
(E) -1/3

CrackverbalGMAT · Answer

Solution: 
 
Given line is 4y + 12x = 48 and we must first reduce this to the form y = mx + c to proceed ahead.

=> y + 3x = 12 on dividing by 4

=> y = - 3x + 12

This line thus has a slope of -3 .

Two perpendicular lines with slopes m1 and m2 have m1 * m2 = -1

=> (-3) * m2 = -1

=>m2 = 1/3  (option b)

Devmitra Sen
GMAT SME

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