$\displaystyle{30}={1}\cdot{30}={2}\cdot{15}={3}\cdot{10}={5}\cdot{6}\usepackage{cmbright}\Huge\$ . The factors whose sum is 17 are 2 and 15. Now rewrite the trinomial and use grouping:

$\displaystyle{{x}}^{{2}}+{2}{x}+{15}{x}+{30}={x}{\left({x}+{2}\right)}+{15}{\left({x}+{2}\right)}={\left({x}+{2}\right)}{\left({x}+{15}\right)}\usepackage{cmbright}\Huge\$