Question

已知x+x分之一=4,求：①x²+x²分之一；②x的四次方+x²+1分之x的二次方

Answer 1

（1）

x^2+1/x^2

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

=4^2-2

=16-2

=14

(2)

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

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

=1/(14+1)

=1/15