Resposta:

[tex]\textsf{Leia abaixo}[/tex]

Explicação passo a passo:

[tex]\sf a = 7/18 \Leftrightarrow b = 5/8 \Leftrightarrow c = 2/9[/tex]

[tex]\sf (3a + b - 2c)^2 - (2a - 3c)^2 + 5(c - a)(a + c) - 2 + b(2a - b)[/tex]

[tex]\sf (9a^2 + 6ab - 12ac + b^2 - 4bc + 4c^2) - (2a - 3c)^2 + (5c^2 - 5a^2) - 2 + (2ab - b^2)[/tex]

[tex]\sf (9a^2 + 6ab - 12ac + b^2 - 4bc + 4c^2) - (4a^2 - 12ac + 9c^2) + (5c^2 - 5a^2) - 2 + (2ab - b^2)[/tex]

[tex]\sf 9a^2 + 6ab - 12ac + b^2 - 4bc + 4c^2 - 4a^2 + 12ac - 9c^2 + 5c^2 - 5a^2 - 2 + 2ab - b^2[/tex]

[tex]\sf 6ab - 12ac + b^2 - 4bc + 4c^2 + 12ac - 9c^2 + 5c^2 - 2 + 2ab - b^2[/tex]

[tex]\sf 6ab - 12ac - 4bc + 4c^2 + 12ac - 9c^2 + 5c^2 - 2 + 2ab[/tex]

[tex]\sf 6ab - 12ac - 4bc + 12ac - 2 + 2ab[/tex]

[tex]\sf 6ab - 4bc - 2 + 2ab[/tex]

[tex]\sf 8ab - 4bc - 2[/tex]

[tex]\sf \not8\:.\left(\dfrac{7}{18}\:.\:\dfrac{5}{\not8}\right) - \not4\:.\left(\dfrac{5}{\not8}\:.\:\dfrac{\not2}{9}\right) - 2[/tex]

[tex]\sf \dfrac{35}{18} - \dfrac{5}{9}\right) - 2[/tex]

[tex]\sf \dfrac{35}{18} - \dfrac{10}{18} - \dfrac{36}{18}[/tex]

[tex]\boxed{\boxed{\sf -\dfrac{11}{18}}}[/tex]