1.已知x^2-2x-1=0,求2x^3-3x^2-4x+2的值
问题描述:
1.已知x^2-2x-1=0,求2x^3-3x^2-4x+2的值
2.因式分解
m^3/9+m+2m^2/3
9a^2-b-b^2-3a
答
x^2-2x-1=0x^2-2x=12x^3-3x^2-4x+2=2x^3-4x^2+x^2-4x+2=2x(x^2-2x)+x^2-4x+2=2x+x^2-4x+2=x^2-2x+2=1+2=3m^3/9+m+2m^2/3 =(1/9)m(m^2+6m+9)=m(m+3)^2/99a^2-b-b^2-3a=(3a+b)(3a-b)-(3a+b)=(3a+b)(3a-b-1)