先化简后求值(x-3)/(2x-4)÷[5/(x-2)-x-2],其中x=√2-3
原式=(x-3)/(2x-4)÷[5-(x²-4)]/(x-2)=(x-3)/[2(x-2)]×(x-2)/[5(x²-4)]=(x-3)/[10(x-2)(x+2)]
=(√2-6)/[10(√2-5)(√2-1)]=(√2-6)/[10(7-6√2)]=(√2-6)(7+6√2)/(-230)=(30-29√2)/230