William W. answered • 4d

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Since the slope is 4x + 2, then f'(x) = 4x + 2. Integrating both sides (taking the anti-derivative), we get f(x) = 2x^{2} + 2x + C. Since the graph goes through (8, 10) then f(8) = 10 or:

10 = 2(8)^{2} + 2(8) + C

10 = 128 + 16 + C

C = -134 so:

f(x) = 2x^{2} + 2x - 134 and

f(3) = 2(3)^{2} + 2(3) - 134 = -110