n = 1 , y =10 / ((2*1 +1)*(1 + 1)) = 10 / 6 = 5 / 3
n = 2, y = 10 / ((2*2 + 1)*(2+1)) = 10 / 8 = 5 / 4
n = 3, y = 10 / ((2*3 + 1)*(3+1)) = 10 / 28 = 5 / 14
n = 4, y = 10 / ((2*4 + 1)*(4+1)) = 10 / 45 = 2 / 9
n = 5, y = 10 / ((2*5 + 1)*(5+1)) = 10 / 66 = 5 / 33
Одз: x-1≠0 x≠1
x-1>0 x²+2x+3(x-1)/x-1=0
x²+2x+3=0
D=4-12=-8 решений нет
x-1<0 x²+2x+3(-(x-1))/x-1=0
x<1 x²+2x-3=0
x₁+x₂=-2 x₁x₂=-3 x₁=-3 x₂=1-не подходит, т.к. x<1
(х-1)²-(х+3)(х-3)=х²-2х+1-(х²-9)=х²-2х+1-х²+9=-2х+10=-2(х-5)