When the $\text{Newton-Raphson}$ method is applied to solve the equation  $f(x)=x^3+2x-1=0$ ,the solution at the end of the first iteration with the initial guess value as $x_0$ =$1.2$ is
1. $-0.82$
2. $0.49$
3. $0.705$
4. $1.69$