Algebra practice question

Answer: -4

The first line has slope 2/5. The second has slope −k/10, and −k/10 = 2/5 gives k = −4.

Common wrong answers

If you answered 2

2 copies the first coefficient.

If you answered 4

4 has the sign wrong.

If you answered -25

−25 uses the negative reciprocal, which gives perpendicular lines.

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