已知X^-5X+1=0,求X^+X+1/X^+1/X的值.

热心网友

X^-5X+1=0 === x + 1/x = 5 ...(1)X^+X+1/X^+1/X = (x + 1/x)^2 - 2 + (x + 1/x) = 5^2 - 2 + 5 = 28