Answer
$\left (x+\frac{3}{7} \right )\left (x-\frac{1}{7} \right )$.
Work Step by Step
The given expression is
$=x^2-\frac{3}{49}+\frac{2}{7}x$
Rearrange.
$=x^2+\frac{2}{7}x-\frac{3}{49}$
Rewrite $\frac{2}{7}$ as $\frac{3}{7}-\frac{1}{7}$.
$=x^2+\frac{3}{7}x-\frac{1}{7}x-\frac{3}{49}$
Factor.
$=x\left (x+\frac{3}{7} \right )-\frac{1}{7} \left (x+\frac{3}{7} \right )$
$=\left (x+\frac{3}{7} \right )\left (x-\frac{1}{7} \right )$.