已知m^2-2m-1=0 则3m^3-(2m+1)^2-3(m-1)=?

2025-01-19 11:26:54
推荐回答(3个)
回答1:

m^2-2m-1=0 则m^2-2m=1
3m^3-(2m+1)^2-3(m-1)
=3m^3-(4m^2+4m+1)-3(m-1)
=3m^3-4m^2-4m-1-3m+3
=3m^3-4m^2-4m-3m-1+3
=3m^3-4m^2-7m+2
=3m^3-6m^2+2m^2-7m+2
=3m(m^2-2m)+2m^2-7m+2
=3m+2m^2-7m+2
=2m^2-4m+2
=2(m^2-2m)+2
=2+2
=4

回答2:

m^2-2m-1=0, m^2=2m+1
3m^3-(2m+1)^2-3(m-1)
=3m*m^2-(4m^2+4m+1)-3m+3
=3m(2m+1)-4m^2-4m-1-3m+3
=6(2m+1)+3m-4(2m+1)-4m-3m+2
=12m+6-8m-4-4m+2
=4

回答3: