Algebra practice question

Answer: 2

Infinitely many solutions means one equation is a multiple of the other. The second is twice the first in its x-term and constant (6 = 2 × 3, 12 = 2 × 6), so the y-term must match too: 4 = 2k, k = 2.

Common wrong answers

If you answered 1

1 would give 3x + y = 6, not proportional to 6x + 4y = 12.

If you answered 4

4 is the y-coefficient of the second equation; the first equation's coefficient is half of it.

If you answered 8

8 doubles instead of halving.

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