Đáp án+giải thích các bước giải:
a)
$5+18:[5+2*x]=7$
$18:[5+2*x]=7-5$
$18:[5+2*x]=2$
$5+2*x=18:2$
$5+2*x=9$
$2*x=9-5$
$2*x=4$
$x=4:2$
$x=2$
$\text{Vậy x=2}$
b)
$16+3+25:[1+2*x]=3*3$
$19+25:[1+2*x]=9$
$25:[1+2*x]=9-19$
$25:[1+2*x]=-10$
$1+2*x=25:-10$
$1+2*x=\dfrac{-5}{2}$
$2*x=\dfrac{-5}{2}-1$
$2*x=\dfrac{-7}{2}$
$x=\dfrac{-7}{2}:2$
$x=\dfrac{-7}{4}$
$\text{Vậy x=}$$\dfrac{-7}{4}$