Đáp án:
Giải thích các bước giải:
a)$|x+2|=0$
$x+2=0$
$ x=-2$
b)$|x-5|=|-7|$
$|x-5|=7$
$x-5=7$
$x=12$
$x=-2$
c)$|x-3|=7-(-2)$
$|x-3|=9$
$|x-3|=9$
\(\left[ \begin{array}{l}x-3=9\\x-3=-9\end{array} \right.\)
\(\left[ \begin{array}{l}x=12\\x=-6\end{array} \right.\)
d)$(7-x)-(25+7)=-25$
$(7-x)-32=25$
$7-x=57$
$x=-50$
e)$(3x-24).73=2.74$
$3x-24=\dfrac{148}{73}$
$3x=\dfrac{1900}{73}$
$x=\dfrac{1900}{219}$
g)$x-[42+(-28)]=-8$
$x-14=8$
$x=6$
e)|x-3|=|5|+|-7|$
$|x-3|=5+7$
$|x-3|=12$
\(\left[ \begin{array}{l}x-3=12\\x-3=-12\end{array} \right.\)
\(\left[ \begin{array}{l}x=15\\x=-9\end{array} \right.\)
g)$4-(7-x)=x-(13-4)$
$4-(7-x)=x-9$
$7-x=-x+13$
$7-x+x+13=0$
$7=-13(vôlí)$
Vậy pt vô nghiệm
