已知x^2-5x-2=0,则代数式(x-2)^3-(x-1)^2+1/x-2的值为

问题描述:

已知x^2-5x-2=0,则代数式(x-2)^3-(x-1)^2+1/x-2的值为

【(x-2)^3-(x-1)^2+1】/(x-2)
=(x-2)^2-(x^2-2x+1-1)/(x-2)
=x^2-4x+4-(x^2-2x)/(x-2)
=x^2-4x+4-x
=x^2-5x+4
=2+4
=6

原所求代数式为:[(x-2)³-(x-1)²+1]/(x-2)=(x-2)²-[(x-1)²-1]/(x-2)=(x-2)²-[(x-1+1)(x-1-1)]/(x-2)=(x-2)²-x=x²-4x+4-x=x²-5x+4由x²-5x-2=0可得:x²-5x=2因此:...