Algebra practice question

Answer: 29

Write h(x) = mx + b. Then h(3t) − h(t) = m(3t) − m(t) = 2mt, and 2mt = 8t forces m = 4. From h(2) = 9, five more units of x give h(7) = 9 + 5(4) = 29.

Common wrong answers

If you answered 33

From x = 2 to x = 7 is 5 units, not 6: h(7) = 9 + 20 = 29.

If you answered 37

From x = 2 to x = 7 is 5 units, not 7: h(7) = 9 + 5 · 4 = 29.

If you answered 49

The identity gives 2mt = 8t, so the slope is 4, not 8.

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