······这道题不好说啊原式为x^4-14x^2+49=-1+49(x^2+7)^2=48x^2+7=根号48或负根号48x^2=（根号48）-7或负（根号48）-7下面太恶心了······x=根号下{（根号48）-7}或根号下{（负根号48）-7}或负根号下{（...