Solving Absolute Value Systems: |x + 3| = |2x + 6| with |x| = 3

Question

{x+3=2x+6x=3 \begin{cases} |x+3|=|2x+6| \\ \lvert x\rvert=3 \end{cases}

Video Solution

Step-by-Step Solution

To solve this system of equations, we will follow these steps:

  • Step 1: Solve the second equation x=3 |x| = 3 .
  • Step 2: Check both potential solutions from Step 1 in the first equation x+3=2x+6 |x+3| = |2x+6| .

Now, let's work through each step:
Step 1: Solve x=3 |x| = 3 . This gives us two potential solutions: x=3 x = 3 and x=3 x = -3 .

Step 2: Check these solutions in x+3=2x+6 |x+3| = |2x+6| :
- For x=3 x = 3 :
x+3=3+3=6=6|x+3| = |3+3| = |6| = 6 and 2x+6=2(3)+6=6+6=12=12|2x+6| = |2(3)+6| = |6+6| = |12| = 12.
Since 612 6 \neq 12 , x=3 x = 3 does not satisfy the first equation.

- For x=3 x = -3 :
x+3=3+3=0=0|x+3| = |-3+3| = |0| = 0 and 2x+6=2(3)+6=6+6=0=0|2x+6| = |2(-3)+6| = |-6+6| = |0| = 0.
Both sides equal 0, so x=3 x = -3 satisfies the first equation.

Therefore, the solution to the system of equations is x=3 x = -3 .

Answer

x=3 x=-3