已知X平方+4X-1＝0,那么2X4次方-4X平方-8X+1的值
问题描述：
已知X平方+4X-1＝0,那么2X4次方-4X平方-8X+1的值
X平方怎么写?
答
x^2 + 4x - 1 = 0求 2x^4 - 4x^2 - 8x + 1 = 2x^4 - 4x^2 - 8x + 1 = 2x^2(x^2 + 4x - 1) - 8x^3 + 2x^2 - 4x^2 - 8x + 1 = - 8x^3 + 2x^2 - 4x^2 - 8x + 1 = -8x(x^2 + 4x - 1) + 32x^2 - 8x - 2x^2 - 8x + 1= 32x^...