a)
[tex]3x - 4xy + {x}^{2} = 3 \times ( - 3) - 4 \times ( - 3) \times ( - 1) + ( - 3)^{2} = - 9 - 4 \times 3 + 9 = - 9 - 12 + 9 = - 12[/tex]
b)
[tex]2(a + 2b) + 4(a - 2b) = 2a + 4b + 4a - 8b = 6a - 4b[/tex]
[tex]6a - 4b = 6 \times ( - 2) - 4 \times 1 = - 12 - 4 = - 16[/tex]
