Home › US High School › Mathematics › Absolute Value Equations and Inequalities › Solve the equation absolute value of 2x - 3 equa…
Solve the equation absolute value of 2x - 3 equals 7.
Ax is 5 or x is -2
Bx is 5 or x is -5
Cx is 2 or x is -2
Dx is 5 or x is 2
Answer & Solution
Correct answer: A. x is 5 or x is -2
1. The absolute value is already alone on the left, so no isolating is needed.
2. The expression inside can be 7 units from zero in either direction.
3. Write the two equivalent equations: 2x minus 3 equals 7, and 2x minus 3 equals negative 7.
4. From the first, 2x equals 10, so x is 5.
5. From the second, 2x equals negative 4, so x is negative 2.
6. Checking x equal to 5 gives the absolute value of 7, and x equal to negative 2 gives the absolute value of negative 7, both equal to 7.
7. Answering 5 or negative 5 flips the sign of the answer rather than of the expression inside.
8. Answering 2 or negative 2 solves only for the second case and mislabels it.
9. Answering 5 or 2 keeps two positive roots and misses the negative branch entirely.
_Source: OpenStax Intermediate Algebra (CC BY 4.0), Ch 2 "Solving Linear Equations", section 2.7 Solve Absolute Value Inequalities_