Выражение (с+1/с)^2-2 (m-2/m)^2-(m+2/m)^2 (x/у+у/х)^2-(x^2/у^2 + у^2/х^2) (a+a+1/а)^2-(a-a+1/а)^2

1. c^2+2 + 1/ c ^2 -2 = c^2 +1/c^2
2. ( m - 2/m)^2- (m +2/m ) ^2 =  2m *( -4/m) = -8
3. (x/y+y/x)^2 - ( x^2 /y^2 +y^2/x^2 ) = 2*(x/y)*(y/x) = 2
4. (a+a +1/a)^2 -(a-a +1/a)^2 =4a^2 + 4a/a + (1/a)^2 - (1/a)^2 = 4( a^2 +1)

(a+a+1/a)^2-(a-a+1/a)^2=(a+a+1/a+a-a+1/a)*(a+a+1/a-a+a-1/a)=(2a+2/a)*(2a)=4a^2+4a/a=4a^2+4=4(a^2+1)