Simplify Denominator: Simplify the denominator of the integrand.The denominator is x2−3x+2. We can factor the quadratic inside the square root to see if it simplifies further.x2−3x+2=(x−1)(x−2)So, x2−3x+2=(x−1)(x−2)
Check Domain: Check the domain of the integrand.Since we have a square root in the denominator, we need to ensure that the expression inside the square root is non-negative for all x in the interval [0,1].(x−1)(x−2)≤0 for x in [0,1] because both (x−1) and (x−2) are negative in this interval. Therefore, the square root is well-defined and real.
Set Up Integral: Set up the integral.We are looking to evaluate the integral from 0 to 1 of the function (3x3−x2+2x−4)/x2−3x+2.∫01(x−1)(x−2)3x3−x2+2x−4dx
Simplify Integrand: Attempt to simplify the integrand.The integrand does not simplify easily, and there is no obvious substitution that will cancel the terms in the numerator with the denominator. This suggests that we may need to use a more advanced technique, such as partial fractions or trigonometric substitution, to evaluate the integral.
Trig Substitution: Recognize the need for a trigonometric substitution. Given the form of the denominator, (x−1)(x−2), a trigonometric substitution might be appropriate. However, the form does not match the standard forms for trigonometric substitution directly. We need to complete the square in the denominator to see if a substitution becomes apparent.
Complete Square: Complete the square in the denominator.To complete the square for x2−3x+2, we take the coefficient of x, which is −3, divide it by 2 to get −23, and square it to get 49. We then add and subtract 49 inside the square root to complete the square.x2−3x+2=x2−3x+49−49+2=(x−23)2−41
Apply Substitution: Apply trigonometric substitution.Now that we have the form (x−23)2−41, we can use the substitution x−23=21sec(θ) to simplify the square root.Let x−23=21sec(θ), then dx=21sec(θ)tan(θ)dθ.
Change Limits: Change the limits of integration.When we change the variable of integration from x to θ, we also need to change the limits of integration. For x=0, we have 0−23=(21)sec(θ), which gives sec(θ)=−3. This is not possible since sec(θ) is always positive or negative infinity, indicating a potential error in our substitution choice. We need to reassess our substitution strategy.
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