Tìm x, biết: a) x + (-1/5) = -4/5 b) 3,7 - x = 7/10 c) x.3/2 = 2,4 c) 3,2 : x = -6/11

* Hướng dẫn giải

$$\begin{gathered} a) x+\left(-\frac{1}{5}\right)=\frac{-4}{15} \\ x=\frac{-4}{15}-\left(-\frac{1}{5}\right) \\ x=\frac{-4}{15}+\frac{1}{5} \\ x=\frac{-4}{15}+\frac{3}{15} \\ x=\frac{-1}{15} \end{gathered}$$

Vậy $x=\frac{-1}{15}$

$$\begin{gathered} b) 3,7-x=\frac{7}{10} \\ 3,7 – x = 0,7 \\ x = 3,7 – 0,7 \\ x = 3. \end{gathered}$$

Vậy x = 3

$$\begin{gathered} c) x.\frac{3}{2}=2,4 \\ x=2,4:\frac{3}{2} \\ x=\frac{12}{5}.\frac{2}{3} \\ x=\frac{8}{5} \end{gathered}$$

Vậy $x=\frac{8}{5}$

$$\begin{gathered} d) 3,2:x=-\frac{6}{11} \\ x=3,2:\left(-\frac{6}{11}\right) \\ x=\frac{16}{5}.\left(-\frac{11}{6}\right) \\ x=-\frac{88}{15} \end{gathered}$$

Vậy $x=-\frac{88}{15}$