>>583
(1) (a+b+c)^2=a^2+b^2+c^2+2(bc+ca+ab)
(2) (bc+ca+ab)^2= b^2*c^2* c^2*a^2+ a^2*b^2 + abc(a+b+c)
(a^2+b^2+c^2)^2=a^4+b^4+c^4+ 2(b^2*c^2* c^2*a^2+a^2*b^2)
(3) a｛(1/b)+(1/c)｝+b｛(1/c)+(1/a)｝+c｛(1/a)+(1/b)｝
=(a+c)/b + (a+b)/c + (b+c)/a
=(-b)/b +(-c)/c +(-a)/a