证明：a、b、c互不相等,由基本不等式,得：a^4+b^4+c^4=1/2(a^4+b^4+b^4+c^4+c^4+a^4)>1/2(2a²b²+2b²c²+2c²a²)=a²b²+b²c²+c²a²=1/2(a²b²+c&s...