AlgebraVery hardConstants for a dependent system
Algebra practice question
The system ax + 3y = 12 and 4x + 6y = k, where a and k are constants, has infinitely many solutions. What is the value of a + k?
Answer: 26
The second equation must be a multiple of the first: 6 = 2 × 3, so a = 4/2 = 2 and k = 2 × 12 = 24. Then a + k = 26.
Common wrong answers
- If you answered 2
- 2 is a alone.
- If you answered 14
- 14 uses a = 2 with k = 12, forgetting to double the constant.
- If you answered 28
- 28 uses a = 4 instead of 2.
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