Question

Answer 1

Gọi số cần tìm là x

Theo đề, ta có: 3/7+39/x=9/8

\(\Leftrightarrow\dfrac{39}{x}=\dfrac{9}{8}-\dfrac{3}{7}=\dfrac{63}{56}-\dfrac{24}{56}=\dfrac{39}{56}\)

hay x=56

Answer 2

56

Answer 3

56

Answer 4

\(\dfrac{-3}{7} - \dfrac{39}{?} = \dfrac{-9}{8} \)

\(\Rightarrow \dfrac{-3}{7} - \dfrac{-9}{8} = \dfrac{39}{?}\)

\(\Rightarrow \dfrac{-3}{7} + \dfrac{9}{8} = \dfrac{39}{?} \)

 

\( \Rightarrow\dfrac{-24 + 63}{56} = \dfrac{39}{?}\)

\(\Rightarrow \dfrac{39}{56}=\dfrac{39}{?}\)

\(\Rightarrow \) \(? = 56\)

Vậy cần điền số \(56\) vào ô trống 

Answer 5

Gọi ô trống là \(x\)

\(\Rightarrow-\dfrac{3}{7}-\dfrac{39}{x}=-\dfrac{9}{8}\)

\(\Rightarrow\dfrac{-39x}{56}=-\dfrac{9}{8}+\dfrac{3}{7}=-\dfrac{39}{56}\)

\(\Rightarrow x=56\)

Vậy chỗ trống cần tìm là \(56\).