原式=(x-3)²/(x-3)(x+2)÷(x+3)(x-3)/(x-5)(x+2)*(x+3)/2(x-5)
=(x-3)/(x+2)*(x-5)(x+2)/(x+3)(x-3)*(x+3)/2(x-5)
=(x-5)/(x+3)*(x+3)/2(x-5)
=1/2