giúp mình với ae ơi

Đáp án:

$\begin{array}{l}a. \ |2x-5|=13\\\rightarrow 2x-5=\pm13\\\rightarrow \left[\begin{array}{l}2x-5=13\\2x-5=-13\end{array}\right.\\\rightarrow \left[\begin{array}{l}x=9\\x=-4\end{array}\right.\\\text{Vậy} \ x\in\{-4;9\}\\b. \ |7x+3|=66\\\rightarrow 7x+3=\pm66\\\rightarrow \left[\begin{array}{l}7x+3=66\\7x+3=-66\end{array}\right.\\\rightarrow \left[\begin{array}{l}x=9\\x=-\dfrac{69}{7}\end{array}\right.\\\text{Vậy} \ x\in\left\{-\dfrac{69}{7};9\right\}\\c. \ |5x-2|\leqslant13\\\rightarrow \left[\begin{array}{l}5x-2\leqslant13\\-(5x-2)\leqslant13\end{array}\right.\\\rightarrow \left[\begin{array}{l}x\leqslant3\\x\geqslant-\dfrac{11}{5}\end{array}\right.\\\rightarrow -\dfrac{11}{5}\leqslant x\leqslant3\\\text{Vậy} \ -\dfrac{11}{5}\leqslant x\leqslant3\end{array}$