Question

[Tuyết Minh Đạt]

 mọi người giúp mik làm hết bài 16 đi ạ. mình đang cần gấp ạ 

Answer 1

[HT.Phong (9A5)]

Bài 16:

1) \(\dfrac{7}{x}=\dfrac{1}{15}+\dfrac{1}{6}\left(x\ne0\right)\)

\(\Rightarrow\dfrac{7}{x}=\dfrac{7}{30}\)

\(\Rightarrow x=7:\dfrac{7}{30}\)

\(\Rightarrow x=30\)

2) \(\dfrac{x}{4}-\dfrac{1}{2}=\dfrac{5}{12}\)

\(\Rightarrow\dfrac{x}{4}=\dfrac{5}{12}+\dfrac{1}{2}\)

\(\Rightarrow\dfrac{x}{4}=\dfrac{11}{12}\)

\(\Rightarrow x=\dfrac{11}{12}\cdot4=\dfrac{11}{3}\)

3) \(\dfrac{9}{14}-\dfrac{x}{7}:\dfrac{5}{3}=\dfrac{3}{14}\)

\(\Rightarrow\dfrac{x}{7}:\dfrac{5}{3}=\dfrac{9}{14}-\dfrac{3}{14}\)

\(\Rightarrow\dfrac{x}{7}:\dfrac{5}{3}=\dfrac{6}{14}=\dfrac{3}{7}\)

\(\Rightarrow\dfrac{x}{7}=\dfrac{3}{7}\cdot\dfrac{5}{3}=\dfrac{5}{7}\)

\(\Rightarrow x=\dfrac{5}{7}\cdot7=5\)

4) \(\dfrac{x}{70}=\dfrac{2}{5}+\dfrac{3}{7}\)

\(\Rightarrow\dfrac{x}{70}=\dfrac{29}{35}\)

\(\Rightarrow x=70\cdot\dfrac{29}{35}\)

\(\Rightarrow x=2\cdot29=58\)

5) \(\dfrac{7}{12}:\left(\dfrac{1}{6}-\dfrac{1}{x}\right)=7\left(x\ne0\right)\)

\(\Rightarrow\dfrac{1}{6}-\dfrac{1}{x}=\dfrac{7}{12}:7\) 

\(\Rightarrow\dfrac{1}{6}-\dfrac{1}{x}=\dfrac{1}{12}\)

\(\Rightarrow\dfrac{1}{x}=\dfrac{1}{6}-\dfrac{1}{12}\)

\(\Rightarrow\dfrac{1}{x}=\dfrac{1}{12}\)

\(\Rightarrow x=1:\dfrac{1}{12}=12\)