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a, 13 - 18 - ( - 42 ) -1 5 = 22

c,(-8 ) ^ 3 : ( - 8 ) ^ 2 +8 = 0

câu a=22 nhé

a ) 13 - 18 - ( - 42 ) - 15    

= 13 - 18 + 42 - 15        

= -5 + 42 - 15                  

= 37 - 15                      

= 22                             

cảm ơn bạn nhiều

\(a,13-18-\left(-42\right)-15\)

\(=13-18+42-15\)

\(=\left(13-15\right)-\left(18+42\right)\)

\(=-2-60\)

\(=-62\)

\(b,369-4\left[\left(-5\right)+4.\left(-8\right)\right]\)

\(=369-4\left[\left(-5\right)+\left(-32\right)\right]\)

\(=369-4.\left(-37\right)\)

\(=369-\left(-148\right)\)

\(=369+148\)

\(=517\)

\(c,\left(-8\right)^3:\left(-8\right)^2+8\)

\(=-512:64+8\)

\(=-8+8\)

\(=0\)

\(d,\left(-12\right)\left(-13\right)+13.\left(-29\right)\)

\(=156+-377\)

\(=156-377\)

\(=-221\)

\(-10< x< 8\)

\(\Rightarrow x\in\left\{-9;-8;...;7\right\}\)

\(x=-9+\left(-8\right)+...+7\)

\(\Rightarrow x=\left(-9\right)+\left(-8\right)=-17\)

P/s: Các câu còn lại tương tự ((:

a, \(-6x=18\)

\(\Rightarrow-x=3\)

\(\Rightarrow x=-3\)

b, \(2x-\left(-3\right)=7\)

\(2x+3=7\)

\(\Rightarrow2x=4\)

\(\Rightarrow x=2\)

c, \(\left(x-5\right)\left(x+6\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-5=0\\x+6=0\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=-6\end{cases}}}\)

a, \(13-18-\left(-42\right)-15\)

\(=13-18+42-15\)

\(=-5+41-15=36-15=21\)

b, \(369-4.\left[\left(-5\right)+4\left(-8\right)\right]\)

\(=369-4.\left[\left(-5\right)+\left(-32\right)\right]\)

\(=369-4.\left(-37\right)\) \(=369-\left(-148\right)=369+148=517\)

c, \(\left(-8\right)^3:\left(-8\right)^2+8\)

\(=\left(-8\right)+8=0\)

d, \(\left(-12\right)\left(-13\right)+13\left(-29\right)\)

\(=\left(-12\right).\left(-13\right)+\left(-13\right).29\)

\(=\left(-13\right)\left[\left(-12\right)+29\right]\)

\(=\left(-13\right).17=-221\)

PP/ss: Có thể tính sai ((:

Bài 13: 

a: =>20-x=15-8+13=20

hay x=0

cái này dễ mak bn,hok lý thuyết ik,nhưng mk bt là bn bt lm bài này

1) 13-18-(-42)-15

=13-18+42-15

=22

1) 13-18-(-42)-15

= 13-18+42-15

= 22

2) 369-4[(-5)+4.(-8)]

= 369-4(-5-32)

=369+20-128

=261

3) (-8)³ :_(-8)²+8( đề cứ sao sao ấy bạn :D)

4) (-12).(-13)+13.(-29)

=13(12-29)

=13.-17

=-221

zài zữ

B1:

\(-5-12=-17\)

\(\left(-4\right).14=-56\)

\(6-12=-6\)

a, \(13-18-\left(-42\right)-15\)

\(=13-18+42-15\)

\(=-5+41-15=36-15=21\)

b, \(369-4.\left[\left(-5\right)+4\left(-8\right)\right]\)

\(=369-4.\left[\left(-5\right)+\left(-32\right)\right]\)

\(=369-4.\left(-37\right)\)

\(=369-\left(-148\right)=369+148=517\)

c, \(\left(-8\right)^3:\left(-8\right)^2+8\)

\(=\left(-8\right)+8=0\)

d, \(\left(-12\right)\left(-13\right)+13\left(-29\right)\)

\(=\left(-12\right).\left(-13\right)+\left(-13\right).29\)

\(=\left(-13\right)\left[\left(-12\right)+29\right]\)

\(=\left(-13\right).17=-221\)

PP/ss: Có thể tính sai ((:

Bài 2 : a, x = -36/9 = -4

b, đề sai 

c, <=> -2 =< x =< -3 => x = -1 

Bài 1: 

a: 2/8=9/36; 2/9=8/36; 8/2=36/9; 9/2=36/8

b: -2/4=9/-18; -2/9=4/-18; 4/-2=-18/9; 9/-2=-18/4

Bài 2: 

a: =>x/3=-4/3

hay x=-4

Câu b đề sai rồi bạn