已知:x+1/x=4,求值:x²/x⁴+x²+1

问题描述:

已知:x+1/x=4,求值:x²/x⁴+x²+1

=x^2+1/x^2+1=x^2+1/x^2-2+2+1=(x+1/x)^2-1=15