\[ -3.5 \cdot 2 + 6 = -7 + 6 = -1 \]
\[ -3.5 \cdot (-3) + 6 = 10.5 + 6 = 16.5 \]
\[ -3.5 \cdot 0.4 + 6 = -1.4 + 6 = 4.6 \]
Ответ: -1; 16.5; 4.6.