Question

Tìm x biết : 

a) 0,2x + 7,51 = -4,29

b) 1/3 . x + 2/5 . (x + 1 ) = 0

 

Answer 1

\(a,0,2x+7,51=-4,29\)

\(\Rightarrow0,2x=-4,29-7,51\)

\(\Rightarrow0,2x=-11,8\)

\(\Rightarrow x=-11,8:0,2=-59\)

Answer 2

\(b,\text{ }\frac{1}{3}\cdot x+\frac{2}{5}\cdot\left(x+1\right)=0\)

\(\frac{1}{3}\cdot x+\frac{2}{5}\cdot x+\frac{2}{5}=0\)

\(x\left(\frac{1}{3}+\frac{2}{5}\right)+\frac{2}{5}=0\)

\(x\cdot\frac{11}{15}+\frac{2}{5}=0\)

\(x\cdot\frac{11}{15}=0-\frac{2}{5}\)

\(x\cdot\frac{11}{15}=\frac{3}{5}\)

\(x=\frac{3}{5}\text{ : }\frac{11}{15}\)

\(x=\frac{9}{11}\)

Answer 3

\(b,\text{ }\frac{1}{3}\cdot x+\frac{2}{5}\cdot\left(x+1\right)=0\)

\(\frac{1}{3}\cdot x+\frac{2}{5}\cdot x+\frac{2}{5}=0\)

\(x\left(\frac{1}{3}+\frac{2}{5}\right)+\frac{2}{5}=0\)

\(x\cdot\frac{11}{15}+\frac{2}{5}=0\)

\(x\cdot\frac{11}{15}=0-\frac{2}{5}\)

\(x\cdot\frac{11}{15}=\frac{3}{5}\)

\(x=\frac{3}{5}\text{ : }\frac{11}{15}\)

\(x=\frac{9}{11}\)