Преобразуем:
((n+2)^2+n^2+2)/(n+2)=n+2+(n+2)^2/(n+2)-(4n+2)/(n+2)=2n+3-(3n/(n+2))
Существует k меньше n
3n=k*n+2k
1<k<3
k=1 n=1
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Ответ: n=1
1)4 6/23 +2 13/23= 6 19/23,
2)12 19/28 - 5 11/28 =7 7/28,
3) 6 +7/16= 6 7/16,
4) 7/15+8/15=15/15= 1,
5) 13/26 +12/26=35/26=1 9/26.
10,12,20,21,23,30,31,32
1)10,12,20,30,32
2)21,23,31
Q=b1/b2=-1/3
S=b1/1-q
S=3/1-(-1/3)=3/4:3=9/4=2,25