Algebra practice question

Answer: 24

For a linear function, f(a) − f(b) = m(a − b). From f(7) − f(2) = 15, 5m = 15, so m = 3. Then f(11) − f(3) = 3(11 − 3) = 24.

Common wrong answers

If you answered 8

8 is 11 − 3, the change in x, not the change in f.

If you answered 15

15 is the given difference, which spans only 5 units of x, not 8.

If you answered 45

45 comes from multiplying 15 by 3 instead of using the slope on the new gap.

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