Question

Tìm x, biết : 

a) 5,2 . x + \(7\frac{2}{5}\) = \(6\frac{3}{4}\)

b) 2,4 : \(\left(\frac{-1}{2}-x\right)\)= \(1\frac{3}{5}\)

Answer 1

sửa câu a

\(5,2.x+7\frac{2}{5}=6\frac{3}{4}=>\frac{26}{5}.x+\frac{37}{5}=\frac{27}{4}=>\frac{26}{5}.x=\frac{27}{4}-\frac{37}{5}\)

\(\frac{26}{5}.x=-\frac{13}{20}=>x=-\frac{13}{20}:\frac{26}{5}=>x=-\frac{1}{8}\)

vậy \(x=-\frac{1}{8}\)

Answer 2

a) \(5,2\cdot x+7\frac{2}{5}=6\frac{3}{4}\)

=> \(5,2\cdot x=6\frac{3}{4}-7\frac{2}{5}=\frac{27}{4}-\frac{37}{5}=-\frac{13}{20}\)

=> \(x=-\frac{13}{20}:5,2=-\frac{13}{20}:\frac{26}{5}=-\frac{13}{20}\cdot\frac{5}{26}=-\frac{1}{8}\)

b) \(2,4:\left(\frac{-1}{2}-x\right)=1\frac{3}{5}\)

=> \(\frac{-1}{2}-x=2,4:1\frac{3}{5}=\frac{12}{5}:\frac{8}{5}=\frac{12}{5}\cdot\frac{5}{8}=\frac{3}{2}\)

=> \(x=-\frac{1}{2}-\frac{3}{2}=-\frac{4}{2}=-2\)

Answer 3

\(5,2.x+7\frac{5}{6}=6\frac{3}{4}=>\frac{26}{5}.x+\frac{47}{6}=\frac{27}{4}=>\frac{26}{4}.x=\frac{27}{4}-\frac{47}{6}\)

\(\frac{26}{4}.x=-\frac{13}{12}=>x=-\frac{13}{12}:\frac{26}{4}=>x=-\frac{1}{6}\)

vậy \(x=-\frac{1}{6}\)

\(2,4:\left(-\frac{1}{2}-x\right)=1\frac{3}{5}=>\frac{12}{5}:\left(-\frac{1}{2}-x\right)=\frac{8}{5}=>\left(-\frac{1}{2}-x\right)=\frac{12}{5}:\frac{8}{5}\)

\(\left(-\frac{1}{2}-x\right)=\frac{3}{2}=>x=-\frac{1}{2}-\frac{3}{2}=>x=-2\)

vậy \(x=-2\)

Answer 4

\(a,5,2.x+7\frac{2}{5}=6\frac{3}{4}\)

\(5,2.x=6\frac{3}{4}-7\frac{2}{5}\)

\(5,2.x=\frac{-13}{20}\)

\(x=\frac{-13}{20}:5,2\)

\(x=\frac{-1}{8}\)

\(b,2,4:\left(\frac{-1}{2}-x\right)=1\frac{3}{5}\)

\(\frac{-1}{2}-x=2,4:1\frac{3}{5}\)

\(\frac{-1}{2}-x=\frac{3}{2}\)

\(x=\frac{-1}{2}-\frac{3}{2}\)

\(x=-2\)

Học tốt