已知x²+4x-1=0,求2x的四次方+8x³-4x²-8x+1的值

已知x²+4x-1=0,求2x的四次方+8x³-4x²-8x+1的值
已知x²+4x-1=0,求2x的四次方+8x³-4x²-8x+1的值

已知x²+4x-1=0,求2x的四次方+8x³-4x²-8x+1的值
2x的四次方+8x³-4x²-8x+1
=2x的四次方+8x³-2x²-2x²-8x+2-1
=2x²(x²+4x-1)-2(x²+4x-1)-1
=2x²×0-2×0-1
=-1