Question

已知x²-5x+1=0,则x²+1/x²=,[ x-1/x]²=,x四次方+1/x四次方=

Answer 1

x²-5x+1=0

x+1/x=5

x²+2+1/x²=25

x²+1/x²=23

[ x-1/x]²=x²-2+1/x²=23-2=21

x四次方+1/x四次方=[x²+1/x²]²-2=23²-2=527