1) (y+5)/(y-5) +(y-5)/(y+5) =((y+5)(y+5) +(y-5)(y-5)) /(y-5)(y+5) =(y²+10y+25 +y² -10y+25) /(y-5)(y+5) =(2y² +50) /(y-5)(y+5) =2(y²+25) /(y-5)(y+5)
2) (y+5)/(y²+25) *2(y²+25)/(y-5)(y+5) =2(y+5)(y²+25) /(y²+25)(y-5)(y+5) =2/(y-5)
3) 2/(y -5) =2/(4.8 -5) =2/(-0.2) = -2 : 2/10 = -2 *10/2 = -10
ответ: -10