$|\frac{1}{2}-2x|+$ $\frac{2}{3}=$ $\frac{7}{3}$
⇒$|\frac{1}{2}-2x|=$ $\frac{5}{3}$
⇒\(\left[ \begin{array}{l}\frac{1}{2}-2x=\frac{5}{3}\\\frac{1}{2}-2x=\frac{-5}{3}\end{array} \right.\)
⇒\(\left[ \begin{array}{l}2x=\frac{-7}{6}\\2x=\frac{13}{6}\end{array} \right.\) =>\(\left[ \begin{array}{l}x=\frac{-7}{12}\\x=\frac{13}{12}\end{array} \right.\)
Vậy $x=-7/12$ hoặc $x=13/12$
c, $(2x-15)^5=(2x-15)^3$
$⇒$\(\left[ \begin{array}{l}2x-15=1\\2x-15=-1\\2x-15=0\end{array} \right.\) ⇒\(\left[ \begin{array}{l}2x=16\\2x=14\\2x=15\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=8\\x=7\\x=15/2\end{array} \right.\)
Bài 2:
GỌi số cần tim là: $x$
Theo bài, ta có:
$x-2∈$$BC(3;4;5;6)=${$60;120;180;...$}
$⇒x∈${$62;122;182$
mà $x-3$ chia hết cho 7
⇒$x=119$
⇒$x=122$
Vậy số cần tìm là: $122$
