How do you solve -6abs(5-2y) = -9?

1 Answer
Aug 23, 2015

y = 7/4" " or " "y = 13/4

Explanation:

Start by isolating the modulus on one side of the equation. This can be done by dividing both sides by -6

(color(red)(cancel(color(black)(-6))) * |5 - 2y|)/color(red)(cancel(color(black)(-6))) = ((-9))/((-6)

|5 - 2y| = 3/2

Since you're dealing with the absolute value of an expression, you must take into account the fact that the expression can be negative or positive.

  • 5-2y>0 implies |5-2y| = 5 - 2y

Your equation becomes

5 - 2y = 3/2

2y = 5 - 3/2

y = (10 - 3)/2 * 1/2 = color(green)(7/4)

  • 5 - 2y <0 implies |5 - 2y| = -(5-2y)

This time, the equation becomes

-(5 - 2y) = 3/2

-5 + 2y = 3/2

2y = (3 + 10)/2

y = 13/2 * 1/2 = color(green)(13/4)

Your original equation has two possible solutions,

y = 7/4" " or " "y = 13/4