题目

I recently turned fifty,which is young for a tree,midlife for an elephant,and ancient for a sportsman.Fifty is a nice number for the states in the US or for a national speed limit,but it is not a number that I was prepared to have hung on me.Fifty is supposed to be my father’s age,but now I am stuck with this number and everything it means. A few days ago,a friend tried to cheer me up by saying,“Fifty is what forty used to be.”He had made an inspirational point.Am I over the hill?People keep telling me that the hill has been moved,and I keep telling them that the high-jump bar has droppe已知x1，x2是方程x2-2x+a=0的两个实数根，且x1+2x2=3-．（1）求x1，x2及a的值；（2）求x13-3x12+2x1+x2的值．