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Find a fundamental set of solutions {
y_(1),y_(2)}of the equation
x^(2) (d^(2)y)/(dx^(2)) - 13x (dy)/(dx) + 49y=0 in the interval x>0

1 Answer

5 votes
Another Cauchy-Euler ODE.


y=x^r

\implies r(r-1)-13r+49=r^2-14r+49=(r-7)^2=0

\implies r=7

\implies y=C_1x^7+C_2x^7\ln x

where
y_1=x^7 and
y_2=x^7\ln x.

To verify that these solutions are linearly independent, check the Wronskian:


W(y_1,y_2)=\begin{vmatrix}x^7&x^7\ln x\\7x^6&x^6(7\ln x+1)\end{vmatrix}=x^(13)

and so the solutions are indeed independent.
User JasonY
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