Упр.846 ГДЗ Никольский Потапов 7 класс (Алгебра)

Задача

а) $$\left(14{,}05-1\frac{1}{4}\right):0{,}04-13{,}8\cdot13$$; б) $$\left(1{,}75:\frac{2}{3}-1\frac{3}{4}:1{,}25\right)\cdot6$$; в) $$\left(2-\frac{1}{4}\cdot0{,}8\right):\left(0{,}16:\frac{1}{2}+0{,}01\right)$$; г) $$3\frac{3}{4}\cdot12+(2{,}55+2{,}7)\cdot\left(0{,}1-\frac{1}{80}\right)$$.

Подробный ответ

а)

$$(14{,}05-1\tfrac{1}{4}):0{,}04-13{,}8\cdot 13$$
$$(14{,}05-1{,}25):0{,}04-179{,}4$$
$$12{,}8:0{,}04-179{,}4$$
$$320-179{,}4=140{,}6$$

б)

$$(1{,}75:\tfrac{2}{3}-1\tfrac{3}{4}:1{,}25)\cdot 6$$
$$\left(\tfrac{7}{4}:\tfrac{2}{3}-\tfrac{7}{4}:\tfrac{5}{4}\right)\cdot 6$$
$$\left(\tfrac{21}{8}-\tfrac{7}{5}\right)\cdot 6$$
$$\left(\tfrac{105-56}{40}\right)\cdot 6 = \tfrac{49}{40}\cdot 6 = \tfrac{147}{20} = 7\tfrac{7}{20}$$

в)

$$(2-\tfrac{1}{4}\cdot 0{,}8):(0{,}16:\tfrac{1}{2}+0{,}01)$$
$$(2-0{,}25\cdot 0{,}8):(0{,}32+0{,}01)$$
$$(2-0{,}2):0{,}33$$
$$1{,}8:0{,}33=\tfrac{1{,}8}{0{,}33}=\tfrac{180}{33}=\tfrac{60}{11}=5\tfrac{5}{11}$$

г)

$$3\tfrac{3}{4}\cdot 12+(2{,}55+2{,}7)\cdot \left(0{,}1-\tfrac{1}{80}\right)$$
$$\tfrac{15}{4}\cdot 12+5{,}25\cdot \left(\tfrac{1}{10}-\tfrac{1}{80}\right)$$
$$45+5{,}25\cdot \tfrac{7}{80}$$
$$45+\tfrac{525}{100}\cdot \tfrac{7}{80} = 45+\tfrac{147}{320} = 45\tfrac{147}{320}$$