C..2 $B2r@OE*78?t$r;}$D@~7?>oHyJ,J}Dx<0(B (1)$B@5B'$N>l9g(B

$B@~7?>oHyJ,J}Dx<0(B

$$a(x)y''+b(x)y'+c(x)y=0$$

$B$K$*$$$F!"$9$Y$F$N78?t$O3+1_HW(B $\vert x-x_0\vert<r_0$ $B$G@5B'(B ($B%Y%-5i?tE83+2DG=(B) $B$H$9$k!#(B $B$3$N$H$-(B $a(x_0)\ne 0$ $B$N$H$-(B $x_0$ $B$r@5B'E@!"(B $a(x_0)=0$ $B$N$H$-(B $x_0$ $B$rFC0[E@$H8F$V!#(B

$x_0$ $B$,@5B'E@$G$"$k>l9g!"(B $p(x):=b(x)/a(x)$, $q(x):=c(x)/a(x)$ $B$H$*$/$3$H$G!"(B

$$y''+p(x)y'+q(x)y=0$$

$B$HJQ7A$G$-$k!#(B $B==J,>.$5$$(B $r>0$ $B$,B8:_$7$F!"(B $p(x)$, $q(x)$ $B$O(B $\vert x-x_0\vert<r$ $B$G@5B'$G$"$k!#(B