Упр.17.4 ГДЗ Рабочая тетрадь Зубарева Мордкович 6 класс Экзамен (Математика)

Раскроем скобки и упростим выражения.

1. $$\begin{aligned} (84-27)-(39-27)-(84-39) &= 84-27-39+27-84+39 \\ &= 0 \end{aligned}$$
2. $$\begin{aligned} -(59-36)-(47-59)+(47-36) &= -59+36-47+59+47-36 \\ &= 0 \end{aligned}$$
3. $$\begin{aligned} 136+(6{,}3+64) &= 136+6{,}3+64 \\ &= (136+64)+6{,}3 \\ &= 200+6{,}3 \\ &= 206{,}3 \end{aligned}$$
4. $$\begin{aligned} (3{,}7+4{,}96)-(3{,}7-3{,}04) &= 3{,}7+4{,}96-3{,}7+3{,}04 \\ &= 4{,}96+3{,}04 \\ &= 8 \end{aligned}$$
5. $$\begin{aligned} -7{,}8-(5{,}39-12{,}8) &= -7{,}8-5{,}39+12{,}8 \\ &= 12{,}8-7{,}8-5{,}39 \\ &= 5-5{,}39 \\ &= -0{,}39 \end{aligned}$$
6. $$\begin{aligned} (3{,}91-6{,}57)+(6{,}57-2{,}91) &= 3{,}91-6{,}57+6{,}57-2{,}91 \\ &= 3{,}91-2{,}91 \\ &= 1 \end{aligned}$$
7. $$\begin{aligned} -\left(7\frac{5}{18}-3{,}8\right)+\left(12\frac{11}{18}+1{,}2\right) &= -7\frac{5}{18}+3{,}8+12\frac{11}{18}+1{,}2 \\ &= \left(-7\frac{5}{18}+12\frac{11}{18}\right)+(3{,}8+1{,}2) \\ &= 5\frac{6}{18}+5 \\ &= 5\frac{1}{3}+5 \\ &= 10\frac{1}{3} \end{aligned}$$
8. $$\begin{aligned} -\left(2\frac{1}{4}-7\frac{2}{9}\right)+\left(8{,}25+2\frac{7}{9}\right) &= -2\frac{1}{4}+7\frac{2}{9}+8{,}25+2\frac{7}{9} \\ &= \left(-2\frac{1}{4}+8{,}25\right)+\left(7\frac{2}{9}+2\frac{7}{9}\right) \\ &= ( -2{,}25+8{,}25 )+10 \\ &= 6+10 \\ &= 16 \end{aligned}$$

Ответ: а) 0; б) 0; в) 206,3; г) 8; д) −0,39; е) 1; ж) 10 1/3; з) 16.