Ответ:

Объяснение:

103. a/(a-b) +a/b=(ab+a²-ab)/(b(a-b))=a²/(ab-b²)

4/x -(5x+4)/(x+2)=(4x+8-5x²-4x)/(x(x+2))=(8-5x²)/(x²+2x)

b/(b-2) -2/(b+2)=(b²+2b-2b+4)/(((b-2)(b+2))=(b²+4)/(b²-4)

105. 1/(a(a+b)) +1/(b(a+b))=(b+a)/(ab(a+b))=1/(ab)

4/b -8/(b(b+2))=(4b+8-8)/(b(b+2))=(4b)/(b(b+2))=4/(b+2)

x/(5(x+7)) -x/(6(x+7))=(6x-5x)/(30(x+7))=x/(30(x+7))

(4n+2)/(3(n-1)) -(5n+3)/(4(n-1))=(16n+8-15n-9)/(12(n-1))=(n-1)/(12(n-1))=1/12