Answer:
33 units²
Explanation:
A (graphing) calculator shows you that f(4) ≈ 8, and f(8) ≈ 8.5. The curve is almost a straight line between, so the area is approximately ...
A = (1/2)(8 + 8.5)(4) = 33
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If you do the integration, it gets a bit messy.

The appropriate answer choice is 33 square units.