2x/(x^2-9)+1/(3-x)-2/(x^2+6x+9)

问题描述:

2x/(x^2-9)+1/(3-x)-2/(x^2+6x+9)

原式化为2x/(x+3)(x-3)-1/(x-3)-2/(x+3)^2=[2x(x+3)-(x+3)^2-2(x-3)]/(x-3)(x+3)^2
=(x+1)(x-3)/(x-3)(x+3)^2
=(x+1)/(x+3)^2