Помогите
Упростите выражение

Ответ:

Объяснение:

1)

(4x-y)/(x²-y²) + 1/(x-y)=  (4x-y) +x+y) / (x²-y²) =5x/ (x²-y²)

2)

y²/(y²-81) - y/(y+9) =y²-y(y-9) / (y²-81) =(y²-y²+9y)/(y²-81)=9y/(y²-81)

3)

10a/(25a²-9) - 1/(5a+3)= [10a-(5a+3)]/(25a²-9)= (10a-5a-3)/(25a²-9)=

=(5a-3)/(25a²-9)=1/(5a+9)

4)

n/(n-7) - n²/(n²-14n+49)=n/(n-7) -n²/(n-7)²=[n(n-7)-n²]/(n-7)²=

=(n²-7n-n²) / (n-7)²=-7n/(n-7)²