Explicație pas cu pas:
[tex] \frac{1}{5} {a}^{2} - \frac{7}{6} a - \frac{6}{5} {a}^{2} - \frac{5}{6} a[/tex]
[tex] \frac{1}{5} {a}^{2} - \frac{6}{5} {a}^{2} - \frac{7}{6} a - \frac{5}{6} a[/tex]
[tex] - \frac{5}{5} {a}^{2} - \frac{2}{6} a[/tex]
[tex] - {a}^{2} - \frac{1}{3} a[/tex]
