How do you solve 8|12x + 7| = 80?

1 Answer
Sep 4, 2017

See a solution process below:

Explanation:

First, divide each side of the equation by color(red)(8) to isolate the absolute value function while keeping the equation balanced:

(8abs(12x + 7))/color(red)(8) = 80/color(red)(8)

(color(red)(cancel(color(black)(8)))abs(12x + 7))/cancel(color(red)(8)) = 10

abs(12x + 7) = 10

The absolute value function takes any term and transforms it to its non-negative form. Therefore, we must solve the term within the absolute value function for both its negative and positive equivalent.

Solution 1:

12x + 7 = -10

12x + 7 - color(red)(7) = -10 - color(red)(7)

12x + 0 = -17

12x = -17

(12x)/color(red)(12) = -17/color(red)(12)

(color(red)(cancel(color(black)(12)))x)/cancel(color(red)(12)) = -17/12

x = -17/12

Solution 2:

12x + 7 = 10

12x + 7 - color(red)(7) = 10 - color(red)(7)

12x + 0 = 3

12x = 3

(12x)/color(red)(12) = 3/color(red)(12)

(color(red)(cancel(color(black)(12)))x)/cancel(color(red)(12)) = 1/4

x = 1/4

The Solutions Are: x = -17/12 and x = 1/4