Question

10. Efectuați: dau coroana​

Answer 1

Sper că este corect ........

Answer 2

$\displaystyle a)~\frac{1}{3} \cdot \frac{6}{13} \cdot 19\frac{1}{2} =\frac{6}{39} \cdot \frac{19 \cdot 2+1}{2} =\frac{6}{39} \cdot \frac{38+1}{2} =\frac{6}{39} \cdot \frac{39}{2} =\frac{6}{2} =3$

$\displaystyle b)~1\frac{1}{4} \cdot \frac{8}{15}\cdot \frac{5}{9} =\frac{1 \cdot 4+1}{4} \cdot \frac{40}{135} =\frac{4+1}{4} \cdot \frac{40}{135}=\frac{5}{4} \cdot \frac{40}{135}=\frac{5\cdot 10}{135}=\frac{50}{135} =\frac{10}{27}$

$\displaystyle c)~\frac{6}{7}\cdot 1\frac{2}{5} \cdot 15=\frac{6}{7} \cdot \frac{1 \cdot5+2}{5} \cdot 15=\frac{6}{7} \cdot \frac{5+2}{5} \cdot 15=\frac{6}{7} \cdot \frac{7}{5} \cdot 15=\frac{90}{5} =18$

$\displaystyle d)~6 \cdot \frac{5}{12} \cdot 1\frac{1}{3} =\frac{5}{2} \cdot \frac{1 \cdot 3+1}{3} =\frac{5}{2} \cdot \frac{3+1}{3} =\frac{5}{2} \cdot \frac{4}{3} =\frac{20}{6} =\frac{10}{3}$