x=(√5-1)/2
2x=√5-1
2x+1=√5
平方,得
4x²+4x+1=5
4x²+4x-4=0
x²+x-1=0
x^4+x^2+2x-1
=x^4+x³-x²-x³+x²+x^2+2x-1 加上x³再减去x³,减去x²再加上x²
=x²(x²+x-1)-x³+2x²+2x-1
=-x³+2x²+2x-1
=-x³-x²+x+x²-x+2x²+2x-1
-x³+2x²+2x-1
= -x³-x²+3x²+x+x-1
= -x³-x²+x+3x²+x-1
= -(x³+x²-x)+3x²+x-1
= -x(x²+x-1)+3x²+x-1