`1`
`a, 3-x=(-27)-(-8)`
`⇔3-x=-19`
`⇔ x=3-(-19)`
`⇔ x=22`
Vậy `x=22`
b`x-17=15-48`
`⇔x-17=-33`
`⇔x =-33+17`
`⇔x =-16`
`Vậy x=16`
c`x-(17-x)=x-7`
`⇔x+17+x=x-7`
`⇔17 =x-2x-7`
`⇔17+7 =-x`
`⇒24 =-x`
`⇒x=-24`
Vậy` x=-24`
e`|x+3|=7`
\(\left[ \begin{array}{l}x+3=7\\x+3=-7\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=4\\x=-10\end{array} \right.\)
Vậy `x=4 hoặc x=-10`
f`|x-5|=(-5)+8`
`⇔|x-5|=3`
\(\left[ \begin{array}{l}x-5=3\\x-5=-3\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=8\\x=2\end{array} \right.\)
Vậy` x=8 `hoặc` x=2`
g,
`|x+12|=2x+8`
\(\left[ \begin{array}{l}x+12=2x+8\\x+12=-2x-8\end{array} \right.\) ↔ \(\left[ \begin{array}{l}x-2x=8-12\\x+2x=-8-12\end{array} \right.\) ↔ \(\left[ \begin{array}{l}x=4\\x=-20/3\end{array} \right.\)
Vì `x in Z``=>` x=4
2
a,`(6×9-15:5)+3×(-7)`
`=(54-3)+(-21)`
`=51+(-21)`
`=30`
b,`30:(-5)×(-6)-8`
`=-6.(-6)-8`
`=36-8`
`=28`
c,`-12+12×(-74)+12×(-25)`
`=-12(1+74+25)`
`=-12.100`
`=-1200`
d,`23×(13-11)-13×(23-11)`
`=23.2-13.12`
`=46-156`
`=-110`
$#minosuke$
