Question

若m的2次方+m-1=o，求m的3次方+2002的值

求救

Answer 1

解方程 得m=(-1加减根号5）/2
m的2次方+m-1=o
m^2+m+1=2
m不等于1，两边乘以m-1
(m-1)(m^2+m+1)=m^3-1=2(m-1)
所以 m的3次方+2002=2(m-1)+1+2002=2m+2001=2000加减根号5

Answer 2

m的2次方+m-1=0,解得m=(-1加减根号5）/2，且m^2=1-m;
所以
m^3+2002
=m(m^2)+2002
=m(1-m)+2002
=m-m^2+2002
=m-(1-m)+2002
=2m+2001
=(-1加减根号5)+2001
=2000加减根号5