Question

tìm x biết:

a,2/5:(-x-1/2)=4/5

b,x+2/11+x+2/12=x+2/13+x+2/14+x+2/15

c,x+1/9+x+2/8=x+3/7+x+4/6

Giúp mk nha,mk cần gấp lắm

Answer 1

Tìm x . biết : 

\(a,\frac{2}{5}:\left(-x-\frac{1}{2}\right)=\frac{4}{5}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{2}{5}:\frac{4}{5}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{2}{5}.\frac{5}{4}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{1}{2}\)

\(\Rightarrow-x=\frac{1}{2}+\frac{1}{2}\)

\(\Rightarrow-x=1\)

\(\Rightarrow x=-1\)

Vậy \(x=-1\)

Answer 2

a. \(\frac{2}{5}.\left(-x-\frac{1}{2}\right)=\frac{4}{5}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{2}{5}:\frac{4}{5}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{2}{5}.\frac{5}{4}\)

\(\Rightarrow-x-\frac{1}{2}=\frac{1}{2}\)

\(\Rightarrow-x=\frac{1}{2}+\frac{1}{2}\)

\(\Rightarrow-x=1\)

\(\Rightarrow x=-1\)