已知x²-5x-2=0求x-2分之(x-2)³-(x-1)²+1=?
问题描述:
已知x²-5x-2=0求x-2分之(x-2)³-(x-1)²+1=?
答
x-2分之(x-2)³-(x-1)²+1=(x-2)²-X=x²-5x+4
因为x²-5x-2=0 所以x²-5x+4=6
答
已知x²-5x-2=0
x^2-5x=2
x-2分之(x-2)³-(x-1)²+1
=[(x-2)^3-(x-1)^2+1]/(x-2)
={(x-2)^3-[(x-1)^2-1]}/(x-2)
={(x-2)^3-[(x-1-1)(x-1+1)]}/(x-2)
={(x-2)^3-[(x-2)x]}/(x-2)
=(x-2)[(x-2)^2-x]/(x-2)
=(x-2)^2-x
=x^2-5x+4
=2+4
=6