Question

Va rog ajutati-ma.Calculati $x^{2} + \frac{1}{ x^{2} }$ stiind ca $x+ \frac{1}{x}=3$.
x apartine lui R

Answer 1

(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