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Find a minimum value for the radius of convergence rho of a power series solution about x₀ to the given differential equation.

(x² - 5x + 6)y" - 3xy' - y =0; x₀ = 1

a. rho = √2/2
b. rho = 2
c. rho = 3
d. rho = 1/2
e. rho = 1

User Learningcs
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1 Answer

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Final answer:

The minimum radius of convergence of the power series solution for the differential equation at x_0 = 1 is the distance to the nearest singular point. Factoring the quadratic portion of the differential equation yields singular points at x = 2 and x = 3, making the minimum radius of convergence 1, which is choice e.

Step-by-step explanation:

The differential equation given is (x² - 5x + 6)y" - 3xy' - y = 0, where we are looking to find the minimum value for the radius of convergence ρ of a power series solution about x0 = 1.

To find the radius of convergence of the power series, we need to identify the singular points of the differential equation. A singular point is where the coefficients of the derivatives in the differential equation become undefined or infinite. In our equation, (x² - 5x + 6) becomes zero for the values of x that turn the quadratic equation to zero.

We factor the quadratic equation x² - 5x + 6:
(x - 2)(x - 3) = 0, which has roots at x = 2 and x = 3. These are the singular points of the differential equation.

Since we are considering a power series solution about x0 = 1, the radius of convergence will be at least the distance to the nearest singular point. The distances to the singular points from x0 = 1 are 1 and 2, respectively.

Therefore, the minimum radius of convergence ρ is 1, corresponding to the nearest singular point.

Thus, the correct answer is e. ρ = 1.

User Nitasha
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