Set up decomposition: We need to integrate the function (x−3)/((x−1)(x−2)). To do this, we will use partial fractions" target="_blank" class="backlink">fraction decomposition to express the integrand as a sum of simpler fractions that we can integrate individually.
Find A and B: First, we set up the partial fraction decomposition:(x−3)/((x−1)(x−2))=(x−1)A+(x−2)BWe need to find the values of A and B.
Plug in x values: To find A and B, we multiply both sides of the equation by (x−1)(x−2) to get rid of the denominators:(x−3)=A(x−2)+B(x−1)
Calculate integrals: Now we will find the values of A and B by plugging in convenient values for x. Let's first plug in x=1: (1−3)=A(1−2)+B(1−1) −2=−A A=2
Integrate x−12: Next, we plug in x=2: (2−3)=A(2−2)+B(2−1) −1=B B=−1
Integrate x−21: Now that we have A and B, we rewrite the original integral:\int\frac{x\(-3\)}{(x\(-1\))(x\(-2\))}dx = \int\left(\frac{\(2\)}{x\(-1\)} - \frac{\(1\)}{x\(-2\)}\right)dx
Combine results: We can now integrate each term separately: \(\int\left(\frac{\(2\)}{x\(-1\)}\right)dx - \int\left(\frac{\(1\)}{x\(-2\)}\right)dx
Final indefinite integral: The integral of \(\frac{2}{x-1} is 2ln∣x−1∣, and the integral of x−21 is ln∣x−2∣. So we have:2ln∣x−1∣−ln∣x−2∣+C, where C is the constant of integration.
Final indefinite integral: The integral of x−12 is 2ln∣x−1∣, and the integral of x−21 is ln∣x−2∣. So we have:2ln∣x−1∣−ln∣x−2∣+C, where C is the constant of integration.We have found the indefinite integral of the given function:∫(x−1)(x−2)x−3dx=2ln∣x−1∣−ln∣x−2∣+C
More problems from Find indefinite integrals using the substitution