[√(n+2)*(√(n+2)+√(n-2))]/[√(n+2)*(√(n+2)-√(n-2))] +
+[√(n+2)*(√(n+2)-√(n-2))]/[√(n+2)*(√(n+2)+√(n-2))]=
=(√(n+2)+√(n-2))/(√(n+2)-√(n-2))+(√(n+2)-√(n-2))/(√(n+2)+√(n-2))=
(n+2+2√(n²-2)+n-2+n+2-2√(n²-2)+n-2)/[(√(n+2)+√(n-2))(√(n+2)-√(n-2))]=
=4n/(n+2-n+2)=4n/4=n
√(√2-1)²+2-√2=√2-1+2-√2=1
5X² + 1 = 0; 5X² = - 1; X² = - 1/5 - решений нет.
Ax-2x=a³-2a²-9a+18
x(a-2)=a²(a-2)-9(a-2)
x(a-2)=(a-2)(a²-9) I÷(a-2) a≠2
x=a²-9.