Correct. The three points are not collinear. The slope between P and Q is $\displaystyle\frac{{{2}-{5}}}{{{2}-{1}}}=\frac{{-{3}}}{{1}}=-{3}\usepackage{cmbright}\Huge\$ , the slope between P and R is $\displaystyle\frac{{-{1}-{5}}}{{{4}-{1}}}=\frac{{-{6}}}{{3}}=-{2}\ne-{3}\usepackage{cmbright}\Huge\$ , and the slope between Q and R is $\displaystyle\frac{{-{1}-{2}}}{{{4}-{2}}}=\frac{{-{3}}}{{2}}\ne-{3}\usepackage{cmbright}\Huge\$ .