/a-(b+1)/a
=-1/a
2.（a-2b）平方/ab-（a+2b）平方/ab
=(a平方-4ab+4b平方)/ab-(a平方+4ab+4b平方)/ab
=-8ab/ab
=-8
3.(5-3x)/(x-2)+(1-x)/(2-x )
=(5-3x)/(x-2)+(x-1)/(x-2)
=(4-2x)/(x-2)
=-2
4.(x平方-y)/（x-3）平方-(9-y)/（3-x）平方
=(x平方-y)/（x-3）平方-(9-y)/（x-3）平方
=(x平方-9)/（x-3）平方
=(x+3)/(x-3)
5.1/2x-4/x平方
=x/2x平方-8/2x平方
=(x-8)/(2x平方)
6.1/(x平方-9)-1/(x平方+6x+9)
=(x+3)/[(x-3)(x+3)平方]-(x-3)/[(x-3)(x+3)平方]
=6/[(x-3)(x+3)平方]
7.y平方/(y-1)-y-1
=y平方/(y-1)-(y平方-1)/(y-1)
=1/(y-1)
8.(m-15)/(m平方-9)-3/(3-m )
=(m-15)/(m平方-9)+(3m+9)/(m平方-9)
=(4m-6)/(m平方-9)