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已知x1、x2是方程x²-3x+1=0的两根则x1²+x2²=?1/x1+1/x2=?
题目详情
已知x1、x2是方程x²-3x+1=0的两根
则
x1²+x2²=?
1/x1+1/x2=?
则
x1²+x2²=?
1/x1+1/x2=?
▼优质解答
答案和解析
x1+x2=3
x1x2=1
x1²+x2²
=(x1+x2)²-2x1x2
=3²-2*1
=9-2
=7
1/x1+1/x2
=(x1+x2)/x1x2
=3/1
=3
x1x2=1
x1²+x2²
=(x1+x2)²-2x1x2
=3²-2*1
=9-2
=7
1/x1+1/x2
=(x1+x2)/x1x2
=3/1
=3
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