AlgebraMediumConstants from a known solution of a system
Algebra practice question
The ordered pair (3, −2) is the solution of the system x + 2y = k and 3x − y = m, where k and m are constants. What is the value of k + m?
Answer: 10
Substitute (3, −2): k = 3 + 2(−2) = −1 and m = 3(3) − (−2) = 11. So k + m = 10.
Common wrong answers
- If you answered 6
- 6 comes from k = 3 − 4 = −1 and m = 9 − 2 = 7, mishandling −(−2).
- If you answered 12
- 12 comes from m = 9 + 2 = 11 and k = 1, dropping the sign on 2y.
- If you answered -11
- −11 comes from k − m.
More Algebra questions
- Medium
A system: 2x + y = 11 and x − y = 1. What is the value of x + y? - Medium
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