ｘ的平方－２ｘ－１＝０求ｘ得多少？

熱心網友

①配方法x^2-2x-1=0x^2-2x=1x^2-2x+1=1+1x^2-2x+1=2(x-1)^2=2x-1=±√2 x1=1-√2 x2=1+√2 ②公式法a=1 b=-2 c=-1x=-b±√(b＾2-4ac)/2ax=2±√(4+4)/2x=1±√2x1=1+√2x2=1-√2兩種你選一種~~~~

熱心網友

x^2-2x-1=0x^2-2x=1x^2-2x+1=1+1x^2-2x+1=2(x-1)^2=2x-1=±√2 x=1±√2

熱心網友

x^2-2x-1=0(x-1)^2-2=0(x-1)^2=2x-1=±√2x=1±√2

熱心網友

x=1+根號2或 1-根號2