在数学解题中,恰当、灵活地使用“1”,能使其某些较为困难的问题迎刃而解,因此总结和掌握“1”在解题中的作用无疑能培养学生的技能和技巧。本文举例说明“1”在不等式证明中的作用。 (1) 用公式x~2+y~2≥2xy及x~3+y~3+z~3≥3xyz(x,y,z∈R~+)证题时要注意运用:1=(?) In mathematics problem solving, the proper and flexible use of “1” can solve some of the more difficult problems. Therefore, summing up and mastering the role of “1” in problem solving can undoubtedly cultivate students’ skills and skills. This article illustrates the role of “1” in the proof of inequality. (1) Use the formulas x~2+y~2≥2xy and x~3+y~3+z~3≥3xyz(x,y,z∈R~+) to apply the test: 1=(? )