a)
[tex]a = 8[/tex]
[tex]5 \times 8 - \frac{1}{2} \times 8 = \\ = 40 - 4 = \\ = 36[/tex]
b)
[tex]b = - 4[/tex]
[tex]2 \times {( - 4)}^{2} + 3 \times ( - 4) = \\ = 2 \times 16 + ( - 12) = \\ = 32 - 12 = \\ = 20[/tex]
c)
[tex]x = 2 \\ y = - 3[/tex]
[tex](2 \times 2 + 4 \times ( - 3))(5 - 2) = \\ = (4 + ( - 12)) \times 3 = \\ = - 8 \times 3 = - 24[/tex]
