Question

Tại sao ra đc kết quả như này vậy

Answer 1

\(\dfrac{3}{12}+\dfrac{9}{v'}=\dfrac{3}{4}\\ \Rightarrow\dfrac{3}{12}+\dfrac{9}{v'}=\dfrac{3}{4}\\ \Rightarrow\dfrac{9}{v'}=\dfrac{3}{4}-\dfrac{3}{12}\\ \Rightarrow\dfrac{9}{v'}=\dfrac{9}{12}-\dfrac{3}{12}\\ \Rightarrow\dfrac{9}{v'}=\dfrac{6}{12}\\ \Rightarrow9:v'=\dfrac{1}{2}\\ \Rightarrow v'=9:\dfrac{1}{2}\\ \Rightarrow v'=9.2\\ \Rightarrow v'=18\)