Correct. $\displaystyle{7}{{x}}^{{2}}+{17}{x}+{6}={7}{{x}}^{{2}}+{3}{x}+{14}{x}+{6}={\left({7}{{x}}^{{2}}+{3}{x}\right)}+{\left({14}{x}+{6}\right)}\usepackage{cmbright}\Huge\$

$\displaystyle={x}{\left({7}{x}+{3}\right)}+{2}{\left({7}{x}+{3}\right)}={\left({7}{x}+{3}\right)}{\left({x}+{2}\right)}\usepackage{cmbright}\Huge\$

The value of a is 3.