Substitution Method: Let's use substitution to solve the integral. We will let u=3x+4, then du=3dx. We need to express x in terms of u and dx in terms of du.
Express x in terms of u: First, we solve for x in terms of u: u=3x+4 implies x=(u−4)/3.
Express dx in terms of du: Next, we express dx in terms of du: since du=3dx, we have dx=3du.
Substitute x and dx: Now we substitute x and dx in the integral: ∫x(3x+4)2dx becomes ∫(3u−4)(u2)(3du).
Simplify the integral: Simplify the integral: \int \left(\frac{u - \(4\)}{\(3\)}\right)u^\(2\left(\frac{du}{3}\right) = \frac{1}{9}\int u^2(u - 4) du = \frac{1}{9}\int (u^3 - 4u^2) du.
Find the antiderivative: Find the antiderivative: (1/9)∫(u3−4u2)du=(1/9)((u4)/4−(4u3)/3)+C.
Simplify the antiderivative: Simplify the antiderivative: (\frac{\(1\)}{\(9\)})\left(\frac{u^\(4\)}{\(4\)} - \frac{\(4\)u^\(3\)}{\(3\)}\right) + C = \left(\frac{\(1\)}{\(36\)}\right)u^\(4 - \left(\frac{4}{27}\right)u^3 + C.
Substitute back for u: Substitute back for u: (361)(3x+4)4−(274)(3x+4)3+C.
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