a,b,c不全为0,满足a+b+c=0,a^3+b^3+c^3=0,求a^5+b^5+c^5的值

4个回答

  • 由a+b+c=0有-c=a+b

    a^3+b^3

    =(a+b)(a^2-ab+ b^2)

    =-c〔(a+b)^2 - 3ab〕

    =-c(c^2-3ab)

    由a^3+b^3+c^3=0有-c^3=a^3+b^3

    故-c^3 = -c(c^2-3ab)

    ①如果c=0,那么由a+b+c=0有a=-b则a^5+b^5+c^5=(-b)^5+b^5+0=0;

    ②如C不为0,两边都可以约去-c时,有c^2= c^2-3ab,即为ab=0,故a或者b为0,不失一般性,设b=0, 则那么由a+b+c=0有a=-c,则a^5+b^5+C^5=(-c)^5+0+c^5=0;

    综上所述:a^5+b^5+c^5 = 0

    O(∩_∩)O~