Absolute value equations with coefficients, step by step

With a number in front of x, an absolute value equation adds one move to the split.

The question

Solve |3x + 9| = 6

3x + 9 = 6or3x + 9 = −6
3x + 9 = 6x = −1
3x + 9 = −6x = −5
x = −5orx = −1
  1. The bars mean the inside is 6 away from zero — so it is 6 OR it is −6. Split into two equations.
  2. Solve the first, 3x + 9 = 6: subtract 9 from both sides: 3x = −3, then divide by 3: x = −1.
  3. Solve the second, 3x + 9 = −6: subtract 9 from both sides: 3x = −15, then divide by 3: x = −5.
  4. So x = −5 or x = −1 — both answers.

How it works.

  1. 01

    The bars mean the inside is 6 away from zero — so it is 6 OR it is −6. Split into two equations.

  2. 02

    Solve the first, 3x + 9 = 6: subtract 9 from both sides: 3x = −3, then divide by 3: x = −1.

  3. 03

    Solve the second, 3x + 9 = −6: subtract 9 from both sides: 3x = −15, then divide by 3: x = −5.

  4. 04

    So x = −5 or x = −1 — both answers.