1) $(x+\frac{1}{x})^2$$=x^2+2+\frac{1}{x^2}=9=>x+\frac{1}{x}=3(x>0)$$(x+\frac{1}{x})^3$$=x^3+\frac{1}{x^3}+3.(x+\frac{1}{x})=27=>x^3+\frac{1}{x^3}=18$ nguyênđỏ x xanh $=x^5+\frac{1}{x^5}+(x+\frac{1}{x})$ nguyên$=> đpcm$
1) $(x+\frac{1}{x})^2$$=x^2+\frac{1}{x^2}
$$+2=9=>x+\frac{1}{x}=3(x>0)$$(x+\frac{1}{x})^3$$=x^3+\frac{1}{x^3}
$$+3.(x+\frac{1}{x})=27=>x^3+\frac{1}{x^3}=18$ nguyênđỏ x xanh $=x^5+\frac{1}{x^5}+(x+\frac{1}{x})$ nguyên$=> đpcm$