x的平方減去x減1等於0,x的五次方分之x的4次方加2x加1 網友廻答:
- x^2-x-1=0
x^2=x 1
x^2-x-1=0
x^2-1=x 平方
(x^2-1)^2=x^2
x^4-2x^2 1=x^2
x^4 1=3x^2
x^4=3x^2-1
x^4=3(x 1)-1
x^4=3x 3-1
x^4=3x 2
x^5=3x^2 2x
x^5=3(x 1) 2x
x^5=3x 3 2x
x^5=5x 3
(x^4 2x 1)/x^5
=(3x^2 2x)/x^5
=[3(x 1) 2x]/x^5
=[3x 3 2x]/x^5
=(5x 3)/(5x 3)
=1
網友廻答:
- x²-x-1=0,所以x²=x 1,x^4=(x 1)²=x² 2x 1=x 1 2x 1=3x 2,x^5=(3x 2)x=3x² 2x=3(x 1) 2x=5x 3(x^4 2x 1)/x^5=(3x 2 2x 1)/(5x 3)=(5x 3)/(5x 3)=1
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