Упр.189 Вариант 3 Дидактические материалы ГДЗ Мерзляк Полонский 6 класс (Математика)
- Раскройте скобки:
1) $$4(5x+9y-z)$$;
2) $$-6(-a-8b+7c)$$;
3) $$(6p-n-4m)\cdot(-1{,}6)$$;
4) $$(-2{,}6a-b+1{,}4c)\cdot(-m)$$;
5) $$-0{,}7n(7a-2{,}1+5k)$$;
6) $$-24\left(\frac{7}{12}x+0{,}5y-\frac{5}{6}z-0{,}3\right)$$.
1) $$4(5x+9y-z)=4\cdot 5x+4\cdot 9y-4\cdot z=20x+36y-4z$$
2) $$-6(-a-8b+7c)=6a+48b-42c$$
3) $$\begin{aligned}(6p-n-4m)\cdot(-1{,}6)&=-1{,}6\cdot 6p+(-1{,}6)\cdot(-n)+(-1{,}6)\cdot(-4m)\\&=-9{,}6p+1{,}6n+6{,}4m\end{aligned}$$
4) $$\begin{aligned}(-2{,}6a-b+1{,}4c)\cdot(-m)&=2{,}6am+bm-1{,}4cm\end{aligned}$$
5) $$\begin{aligned}-0{,}7n(7a-2{,}1+5k)&=-0{,}7n\cdot 7a-0{,}7n\cdot(-2{,}1)-0{,}7n\cdot 5k\\&=-4{,}9an+1{,}47n-3{,}5nk\end{aligned}$$
6) $$\begin{aligned}-24\left(\frac{7}{12}x+0{,}5y-\frac{5}{6}z-0{,}3\right)&=-24\cdot\frac{7}{12}x-24\cdot 0{,}5y+24\cdot\frac{5}{6}z+24\cdot 0{,}3\\&=-14x-12y+20z+7{,}2\end{aligned}$$
Ответ: 1) $$20x+36y-4z$$; 2) $$6a+48b-42c$$; 3) $$-9{,}6p+1{,}6n+6{,}4m$$; 4) $$2{,}6am+bm-1{,}4cm$$; 5) $$-4{,}9an+1{,}47n-3{,}5nk$$; 6) $$-14x-12y+20z+7{,}2$$.
