已知x^2=x+1,求下列代数式的值:x^5-5x+2
人气:426 ℃ 时间:2020-04-02 21:20:46
解答
x^5
=(x^2)^2 *x
=(x+1)^2 *x
=x^3 +2x^2+x
=x(x+1)+2(x+1)+x
=x^2+x+2x+2+x
=x+1+x+2x+2+x
=5x+3
所以原式=5x+3-5x+2
=5
关键是不停地把x^2转换成x+1
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