Răspunsuri

2014-06-13T18:03:56+03:00
(x+1/x)²= x²+1/x²+2x/x=x²+1/x²+2 
dar x+1/x=3
inlocuind⇒
x²+1/x²+2=(3)²
x²+1/x²=9-2=7