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Evaluate a definite integral of a polynomial using FTC Part 2

Evaluate the definite integral:

∫02(3x3−x+5) dx\int_0^2 (3x^3 - x + 5)\, dx

Find the exact value of this integral.

Hint

Find an antiderivative F(x)F(x) of the integrand term by term, then compute F(2)−F(0)F(2) - F(0).

Step-by-step solution

First find an antiderivative of 3x3−x+53x^3 - x + 5. Using the power rule for antiderivatives, ∫3x3 dx=3x44\int 3x^3\,dx = \frac{3x^4}{4}, ∫−x dx=−x22\int -x\,dx = -\frac{x^2}{2}, and ∫5 dx=5x\int 5\,dx = 5x. So F(x)=3x44−x22+5xF(x) = \frac{3x^4}{4} - \frac{x^2}{2} + 5x.

By FTC Part 2, ∫02(3x3−x+5) dx=F(2)−F(0)\int_0^2 (3x^3-x+5)\,dx = F(2) - F(0). Compute F(2)=3(16)4−42+10=12−2+10=20F(2) = \frac{3(16)}{4} - \frac{4}{2} + 10 = 12 - 2 + 10 = 20, and F(0)=0F(0) = 0. Therefore the value of the integral is 20−0=2020 - 0 = 20.

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