已知:a²-3a+1=0,求a²+1/a²的值
问题描述:
已知:a²-3a+1=0,求a²+1/a²的值
答
a²-3a+1=0
a-3+1/a=0
a+1/a=3
(a+1/a)²=3²
a²+1/a²+2=9
a²+1/a²=7