Q. Вычислить несобственный интеграл или установить его расходимость∫01cos1−xπ⋅(1−x)2dx
Make Substitution: Let's make a substitution to simplify the integral.Let u=1−x, then du=−dx.Rewrite the integral in terms of u.∫01cos(1−xπ)(1−x)2dx=∫10cos(uπ)u2−du
Rewrite Integral: Since we have a negative sign from du and the limits are swapped, we can remove the negative sign by swapping the limits back.∫10cos(π/u)u2−du=∫01cos(π/u)u2du
Evaluate Integral: Now, let's evaluate the integral. ∫01cos(uπ)u2duThis is an improper integral because the integrand becomes unbounded as u approaches 0.We need to take the limit as u approaches 0 from the right.limt→0+∫t1cos(uπ)u2du
Find Antiderivative: To evaluate the limit, we need to find the antiderivative of cos(π/u)/u2. However, this integral does not have an elementary antiderivative, so we cannot proceed with standard integration techniques.
Determine Convergence: Since we cannot find an antiderivative, we need to determine if the integral converges or diverges by other means.We can compare it to a known divergent integral.As u approaches 0, u21 approaches infinity faster than cos(π/u), which is bounded between −1 and 1.Therefore, the integral behaves like u21 near 0, which is a known divergent p-integral for p≤1.
Conclude Divergence: Since the integral behaves like a divergent p-integral near 0, the original integral also diverges.Therefore, we can conclude that the improper integral diverges.
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