2|7 − 7x| = 2x + 4
|7 - 7x| = x + 2
7 - 7x = x + 2 or 7 - 7x = -(x + 2)
-8x = -5 or 7 - 7x = -x - 2
x = 5/8 or -6x = -9
x = 5/8 or x = 9/6
x = 5/8 or x = 3/2
To check for extraneous solutions, we check both solutions in the original equation.
Check solution 5/8:
2|7 - 7x| = 2x + 4
|7 - 7x| = x + 2
|7 - 7 * 5/8| = 5/8 + 2
|56/8 - 35/8| = 5/8 + 16/8
21/8 = 21/8
Solution x = 5/8 works.
Check solution 3/2:
2|7 - 7x| = 2x + 4
|7 - 7x| = x + 2
|7 - 7 * 3/2| = 3/2 + 2
|14/2 - 21/2| = 3/2 + 4/2
|-7/2| = 7/2
7/2 = 7/2
Solution 3/2 also works.
Answer: x = 5/8 or x = 3/2