Question

初二数学题 在线等答案 x+1/x=2 求x2+1/x2 x4+1/x4 的值

x2+1/x2 x4+1/x4 2和4是平方。。

Answer 1

都是2。

x+1/x=2
(x+1/x)^2=4
x^2+1/x^2+2=4
x^2+1/x^2=2

(x^2+1/x^2)^2=4
x^4+1/x^4+2=4
x^4+1/x^4=2

Answer 2

x+1/x=2
平方
x2+2+1/x2=4
x2+1/x2=2

x2+1/x2=2
两边平方
x4+2+1/x4=4
x4+1/x4=2

Answer 3

x+1/x=2,那么X=1
带入就可以了，2+2+0.25=4.25

Answer 4

x^2+(1/x^2)=(x+1/x)^2-2=2^2-2=2;
x^4+(1/x^4)=(x^2+(1/x^2))^2-2=2^2-2=2;

Answer 5

(x^2+1/x^2)=(x+1/x)^2-2=2^2-2=2
(x^4+1/x^4)=(x^2+1/x^2)^2-2=2^2-2=2