Розкрий дужки:
Розв'язок:
1) $-0{,}8a \cdot (-4b + 3c - 0{,}9d) =$
$= -0{,}8a \cdot (-4b) - 0{,}8a \cdot 3c - 0{,}8a \cdot (-0{,}9d) =$
$= 3{,}2ab - 2{,}4ac + 0{,}72ad$;
2) $(0{,}7x - 2{,}5y - 3{,}8z) \cdot (-0{,}4) =$
$= 0{,}7x \cdot (-0{,}4) - 2{,}5y \cdot (-0{,}4) - 3{,}8z \cdot (-0{,}4) =$
$= -0{,}28x + y + 1{,}52z$;
3) $-12 \cdot \left(1\frac{5}{6}t - 1\frac{1}{3}b + 2\frac{1}{2}z\right) =$
$= -12 \cdot \frac{11}{6}t - 12 \cdot \left(-\frac{4}{3}b\right) - 12 \cdot \frac{5}{2}z =$
$= -22t + 16b - 30z$;
4) $\left(-\frac{1}{7}y + 1\frac{1}{2}z - 2\frac{1}{14}t\right) \cdot 14x =$
$= -\frac{1}{7}y \cdot 14x + \frac{3}{2}z \cdot 14x - \frac{29}{14}t \cdot 14x =$
$= -2xy + 21zx - 29tx$.