(x的2次方-9)分之12+(3-x)分之2

1个回答

12/(x+3)(x-3)+2/(3-x)
=12/(x+3)(x-3)-2/(x-3)
=[12-2(x+3)]/(x+3)(x-3)
=2(3-x)/(x+3)(x-3)
=-2/(x+3)