x2-3x+1=0 求x4+1/x4的值

问题描述:

x2-3x+1=0 求x4+1/x4的值

x2-3x+1=0
x-3+1/x=0
x+1/x=3
两边同时平方得:
x2+2+1/x2=9
x2+1/x2=7
两边再同时平方得:
x4+2+1/x4=49
x4+1/x4=47