Identify and Decide: Identify the structure of the integral and decide on a strategy.The integral is a rational function where the numerator degree is less than the denominator degree. This suggests that we can use partial fractions" target="_blank" class="backlink">fraction decomposition to rewrite the integral as a sum of simpler fractions that can be integrated individually.
Perform Decomposition: Perform partial fraction decomposition.We want to express (2x)/((x−1)(x−2)(x+4)) as A/(x−1)+B/(x−2)+C/(x+4), where A, B, and C are constants to be determined.
Clear Fractions and Solve: Multiply both sides by the denominator to clear the fractions and solve for A, B, and C.2x=A(x−2)(x+4)+B(x−1)(x+4)+C(x−1)(x−2)We will now find the values of A, B, and C by plugging in suitable x values that simplify the equation.
Find A Value: Find the value of A by plugging in x=1.2(1)=A(1−2)(1+4)2=A(−1)(5)A=−52
Find B Value: Find the value of B by plugging in x=2.2(2)=B(2−1)(2+4)4=B(1)(6)B=64B=32
Find C Value: Find the value of C by plugging in x=−4.2(−4)=C(−4−1)(−4−2)−8=C(−5)(−6)−8=30CC=30−8C=15−4
Write with Partial Fractions: Write the integral with the determined partial fractions. ∫(x−1)(x−2)(x+4)2xdx=∫x−1−52dx+∫x−232dx+∫x+4−154dx
Integrate Each Term: Integrate each term separately. ∫5−2x−11dx=5−2ln∣x−1∣+C1∫32x−21dx=32ln∣x−2∣+C2∫15−4x+41dx=15−4ln∣x+4∣+C3
Combine and Write Final Answer: Combine the constants and write the final answer.The final answer is the sum of the three integrals with a single constant of integration.(-\frac{\(2\)}{\(5\)})\ln|x\(-1| + (\frac{2}{3})\ln|x−2| + (-\frac{4}{15})\ln|x+4| + C
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