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Evaluating (f+g)(3)(f+g)(3) for f(x)=3x25x+7f(x) = 3x^2 - 5x + 7 and g(x)=x24x3g(x) = x^2 - 4x - 3

To evaluate (f+g)(3)(f + g)(3) for the functions f(x)=3x25x+7f(x) = 3x^2 - 5x + 7 and g(x)=x24x3g(x) = x^2 - 4x - 3, there are two methods. The first method evaluates the combined function (f+g)(x)=4x29x+4(f + g)(x) = 4x^2 - 9x + 4 by substituting x=3x = 3, yielding 4(3)293+4=3627+4=134(3)^2 - 9 \cdot 3 + 4 = 36 - 27 + 4 = 13. The second method evaluates f(3)f(3) and g(3)g(3) separately and adds the results. First, find f(3)=3(3)25(3)+7=2715+7=19f(3) = 3(3)^2 - 5(3) + 7 = 27 - 15 + 7 = 19. Next, find g(3)=(3)24(3)3=9123=6g(3) = (3)^2 - 4(3) - 3 = 9 - 12 - 3 = -6. Finally, add the two values: (f+g)(3)=f(3)+g(3)=19+(6)=13(f + g)(3) = f(3) + g(3) = 19 + (-6) = 13. Both methods produce the same result.

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Updated 2026-04-29

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