To solve the absolute value equation \( |12 - 3x| = |9 + 4x| \), we need to consider the different cases based on the properties of absolute values.
Case 1: \( 12 - 3x = 9 + 4x \)
- Solve for \( x \): \[ 12 - 3x = 9 + 4x \] \[ 12 - 9 = 4x + 3x \] \[ 3 = 7x \] \[ x = \frac{3}{7} \]
Case 2: \( 12 - 3x = -(9 + 4x) \)
- Solve for \( x \): \[ 12 - 3x = -9 - 4x \] \[ 12 + 9 = -4x + 3x \] \[ 21 = -x \] \[ x = -21 \]
Case 3: \( -(12 - 3x) = 9 + 4x \)
- Solve for \( x \): \[ -12 + 3x = 9 + 4x \] \[ -12 - 9 = 4x - 3x \] \[ -21 = x \] (This is the same as Case 2.)
Case 4: \( -(12 - 3x) = -(9 + 4x) \)
- Solve for \( x \): \[ -12 + 3x = -9 - 4x \] \[ -12 + 9 = -4x - 3x \] \[ -3 = -7x \] \[ x = \frac{3}{7} \] (This is the same as Case 1.)
Summary of Solutions
From these cases, we have the solutions:
- \( x = \frac{3}{7} \)
- \( x = -21 \)
Final Answer
The solutions to the equation \( |12 - 3x| = |9 + 4x| \) are \( x = \frac{3}{7} \) and \( x = -21 \).
If we refer to the response options, the correct one is:
x = −21 and x = 3/7