化简求值,若x的平方减x再减1等于0,求x的五次方减5x的值

x²-x-1=0
x²=x+1
x²-x=1
所以
x^5-5x
=x³(x+1)-5x
=x^4+x³-5x
=（x+1）²+x(x+1)-5x
=x²+2x+1+x²+x-5x
=2x²-2x+1
=2(x²-x)+1
=2×1+1
=3