Bài 2
`a) 9−13−(−24)+11`
`=9−13+24+11`
`=31`
`b) 323−6.[3−7.(−9)]`
`=323 −6.[3+63]`
`=323−6.66`
`=323-396`
`=−73`
`c) (−3)^5:(−3)^3−9`
`=(−3)^2−9`
`=9-9=0`
`d)(-8).16-138`
`=−96−138`
`=−234`
`3)`
`a) -15:x=3`
` x=−5`
`b) −3x+8=−7`
`−3x=−15`
`x=5`
`c)`\(\left[ \begin{array}{l}x-6=0\\7-x=0\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=6\\x=7\end{array} \right.\)
Bài 4
Ta có bảng
x - 3 -7 -1 1 7
2y + 1 -1 -7 7 1
x -4 -2 2 10
y -1 -4 3 0
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Ta có bảng
2x-1 -55 -11 -5 -1 1 5 11 55
3y-2 1 5 11 55 -55 -11 -5 -1
x -17 -5 -2 0 1 3 6 28
y ... .... ,,,, .... .... -3 -1 ........