人教A版选修4-5中有证明三元重要不等式:如果a,b,c∈R~+。,那么a~3+b~3+c~3≥3abc时,用了一个恒等式a~3+b~3+c~3-3abc=(1/2)(a+b+c)[(a-b)~2+(a-c)~2+(b-c)~2].(*)这个恒等式特别重要,在数学竞赛中,经常用到.下面仅举2016年江苏赛区的两道赛题.例1若不全相等的三个实数a,b,c满足 There are ternary important inequalities that have been proved in the 4-5 editions of the A version of the Electra: if a,b,c∈R~+. , then when a~3+b~3+c~3≥3abc, use an identity a~3+b~3+c~3-3abc=(1/2)(a+b+c)[(ab )~2+(ac)~2+(bc)~2].(*) This identity is particularly important and is often used in math competitions. The following is only a list of two matches in the Jiangsu Division in 2016. Example 1 Three real numbers a, b, c that are not all equal