已知等價于：m² = 4-m,利用該式降次,所以 m^4 = (4-m)² = m² -8m +16 = (4-m)-8m+16=20-9m,m^3 = m*(4-m)=4m-m²=5m-4,原式=20-9m + 2(5m-4) - m -2009 = -1997.提打錯了 是這個已知m²+m-1=0,求m四次方+2m三次方-m-2009= 對不起哈已知等價于：m² = 1-m， 利用該式降次，所以 m^4 = (1-m)² = m² -2m +1 = (1-m)-2m+1=2-3m，m^3 = m*(1-m)=m-m²=2m-1，原式=2-3m + 2(2m-1) - m -2009 = -2009。