If x + 1/x = 3, x ≠ 0 then the value of x^7 + 1x^7 is

Answer: Option B

$$\begin{array}{rl}& x+\frac{1}{x}=3,x\ne 0\\ & x^2+\frac{1}{x^2}=3^2-2=7\\ & x^4+\frac{1}{x^4}=7^2-2=47\\ & x^3+\frac{1}{x^3}=3^3-3\times 3\\ & =27-9\\ & =18\\ & x^7+\frac{1}{x^7}=\left(x^4+\frac{1}{x^4}\right)\left(x^3+\frac{1}{x^3}\right)-\left(x+\frac{1}{x}\right)\\ & =47\times 18-3\\ & =846-3\\ & =843\end{array}$$