【数学】：已知：x^2-11x+1=0,求x^2+1/x^2的值.
问题描述：
【数学】：已知：x^2-11x+1=0,求x^2+1/x^2的值.
答
X^2-11X+1=0
所以 x^2+1 =11x
两边平方：x^4+1+2x^2=121x^2
x^4+1=119x^2
所以 （x^4+1）/x^2 =119
所以X^2+1/X^2=（x^4+1）/x^2=119
答
x^2-11x+1=0,
x^2/x-11x/x+1/x=0,
x+1/x=11
(x+1/x)^2=121
x^2+1/x^2+2=121
x^2+1/x^2=121-2=119
答
x^2-11x+1=0,则x-11+1/x=0,则x+1/x=11
x^2+1/x^2
=x^2+1/x^2+2-2
=(x+1/x)²-2
=11²-2
=119