Question

x-x的-1次方=2,求x平方+x的-2次方,和是多少?

Answer 1

x-x^(-1)=2

x-1/x=2

x^2+x^(-2)

=x^2+1/x^2

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

因为 x-1/x=2

则

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

=2^2+4

=4+4

=8

答：和是8.