Question

rezolvare
$\frac{2}{7 } - ( - \frac{3}{4} ) \div \frac{7}{8}$
$- \frac{1}{8} \times \frac{32}{3} - \frac{5}{6} \div \frac{5}{2}$


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Answer 1

a)

$\frac{\frac{2}{7}-\left(-\frac{3}{4}\right)}{\frac{7}{8}}$

Aplicăm regula: $-\left(-a\right)=a$

$=\frac{\frac{2}{7}+\frac{3}{4}}{\frac{7}{8}}$

Aplicăm regula fracțiilor: $\frac{a}{\frac{b}{c}}=\frac{a\cdot \:c}{b}$

$=\frac{\left(\frac{2}{7}+\frac{3}{4}\right)\cdot \:8}{7}$

Adunăm:

$\frac{2}{7}+\frac{3}{4}:\quad \frac{29}{28}$

$=\frac{8\cdot \frac{29}{28}}{7}$

Înmulțim și calculăm:

$\frac{29}{28}\cdot \:8 =\frac{29\cdot \:8}{28} =\frac{232}{28} =\frac{58}{7}$

$=\frac{\frac{58}{7}}{7}$

Aplicăm regula fracțiilor:

$\frac{\frac{b}{c}}{a}=\frac{b}{c\:\cdot \:a}$

$=\frac{58}{7\cdot \:7}$

$=\frac{58}{49}$

b)

$-\frac{1}{8}\times \frac{32}{3}-\frac{5}{6}\div \frac{5}{2}$

Aplicăm regula fracțiilor:

$\frac{a}{b}\div \frac{c}{d}=\frac{a}{b}\times \frac{d}{c}$

$=-\frac{1}{8}\times \frac{32}{3}-\frac{5}{6}\times \frac{2}{5}$

$\frac{1}{8}\times \frac{32}{3}=\frac{4}{3}$

$\frac{5}{6}\times \frac{2}{5}=\frac{1}{3}$

$=-\frac{4}{3}-\frac{1}{3}$

Aplicăm regula:

$\frac{a}{c}\pm \frac{b}{c}=\frac{a\pm \:b}{c}$

$=\frac{-4-1}{3}$

$=\frac{-5}{3}$

$=-\frac{5}{3}$

Sper că te-am ajutat!

Succes!