=[(x+2)/x(x-2)-(x-1)/(x-2)²] ×(x+2)(x-2)/(4-x)
=[(x+2)(x-2)-x(x-1)]/x(x-2)² ×(x+2)(x-2)/(4-x)
=(x²-4-x²+x)/x(x-2)×(x+2)/(4-x)
=(x-4)/x(x-2)×(x+2)/(4-x)
=-(x+2)/x(x-2)