please answer this question

2 / (a-1) (a-2) + 3 / (a-1) (a+2) - 4 / (a+2) (a-2)
= [2(a+2) + 3(a-2) - 4(a-1)] / (a-1) (a+2) (a-2)
= (2a + 4 + 3a - 6 - 4a + 4) / (a-1) (a+2) (a-2)
= (a+2) / (a-1) (a+2) (a-2)
= 1 / (a-1) (a-2)

I want to try but I think the question may be not complete.