已知x=根号2-1,求(5-6x-3x^2)/(x^2+2x-3)的值.

已知x=根号2-1,求(5-6x-3x^2)/(x^2+2x-3)的值.
已知x=根号2-1,求(5-6x-3x^2)/(x^2+2x-3)的值.

已知x=根号2-1,求(5-6x-3x^2)/(x^2+2x-3)的值.
x＝√2 －1
x＋1=√2
(x+1)²＝2
x²＋2x＋1＝2
x²＋2x=1
(5-6x-3x²)/(x²+2x-3)
＝[5－3﹙x²＋2x﹚]／[﹙x²+2x﹚-3]
=﹙5-3﹚／﹙1-3﹚
-1