Question

Checking Your Understanding
Consider this equation and the steps taken to solve it.

 –9(a – 5) = –18  (distribute)

 –9a + 45 = –18  (subtract 45)

    –9a = –63  (divide by –9)


    a = 7

What steps might you take to verify the solution? Check all that apply.
Substitute 7 for a.
Pick any value for a and substitute.
Simplify the equation after substituting the value for a.
Verify that a = 7 is correct when the result is a true statement.
Verify that a = 7 is correct when the result is a false statement.

Answer 1

Correct answers:
- Substitute 7 for a.
- Simplify the equation after substituting the value for a.
- Verify that a = 7 is correct when the result is a true statement.

Explanation: To check a solution you substitute the proposed value (7) into the original equation, simplify, and confirm the two sides match (here −9(7−5)=−9·2=−18, which equals −18). Picking any other value or accepting a false resulting statement does not verify the solution.