Răspuns:
Explicație pas cu pas:
Salutare!
[tex]\bf 1\dfrac{1}{4} \cdot \dfrac{2}{5} = \dfrac{4 \cdot 1 +1}{4}\cdot \dfrac{2}{5} = \dfrac{5}{4}\cdot \dfrac{2}{5} =\dfrac{\not5}{\not4}\cdot \dfrac{\not2}{\not5} =\dfrac{1}{2} \cdot \dfrac{1}{1} = \boxed{\boxed{\bf\dfrac{1}{2} }}[/tex]
[tex]\it~~[/tex]
[tex]\bf \dfrac{7}{8}\cdot b=\dfrac{7}{10}\implies 7b\cdot 10=7\cdot 8~\bigg|:7\implies 10b = 8\implies\bigg(\dfrac{8}{10}\bigg)^{(2}\implies \boxed{\boxed{\bf b=\dfrac{4}{5}}}[/tex]
[tex]\it~~~[/tex]
[tex]\bf a\cdot \dfrac{3}{2}= \dfrac{5}{6}\implies 3a\cdot 6= 2\cdot 5~\bigg|:2\implies 9a = 5\implies \boxed{\boxed{\bf a =\dfrac{5}{9}}}[/tex]
[tex]\it~~~[/tex]
[tex]\bf 1\dfrac{1}{4} : \dfrac{2}{5} = \dfrac{4 \cdot 1 +1}{4}:\dfrac{2}{5} = \dfrac{5}{4}:\dfrac{2}{5} =\dfrac{5}{4}\cdot \dfrac{5}{2} = \boxed{\boxed{\bf\dfrac{25}{8} }}[/tex]
[tex]\it~~~[/tex]
[tex]\bf \dfrac{7}{8}: b=\dfrac{7}{10}\implies \dfrac{7}{8}\cdot \dfrac{1}{b}=\dfrac{7}{10} \implies 8b\cdot 7=7\cdot 10~\bigg|:7\implies 8b = 10\implies[/tex]
[tex]\bf \implies 8b = 10\implies\bigg(\dfrac{10}{8}\bigg)^{(2}\implies \boxed{\boxed{\bf b=\dfrac{5}{4}}}[/tex]
[tex]\it~~~[/tex]
[tex]\bf a: \dfrac{3}{2}= \dfrac{5}{6}\implies\dfrac{a}{1} \cdot \dfrac{2}{3}=\dfrac{5}{6}\implies 2a\cdot 6= 3\cdot 5~\bigg|:3\implies 4a = 5\implies \boxed{\boxed{\bf a =\dfrac{5}{4}}}[/tex]
PS: Te rog sa glisezi spre dreapta pentru a vedea toată rezolvarea
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