\(1)\)

\(-3-18\)

\(=-(3+18)\)

\(=-21\)

\(-7\times-5\)

\(=7\times(-1)\times(-5)\)

\(=7\times5\)

\(=35\)

\(5+(-11)\)

\(=5-11\)

\(=-6\)

1,

a) -3 - 18=-21

b) (-7).(-5)=35

c) 5+(-11)=-6

2,

a) -2-13+(-14)-19=-48

b) 221 + 4[(-5).8-4]=45

c) (-2)³.(-2)²+32=0

d) -15.12 - 8.(-12)=-84

3,

a)  x:(-2)=9

=>x      =9.(-2)

=>x      =-18

b)4x+(-8)=24

=>4x     =24-(-8)

=>4x     =32

=>x      =32:4

=>x      =8

c) (3x)(x+7)=0

\(\Rightarrow\hept{\begin{cases}3x=0\\x+7=0\end{cases}\Rightarrow\hept{\begin{cases}x=0:3\\x=0-7\end{cases}\Rightarrow}\hept{\begin{cases}x=0\\x=-7\end{cases}}}\)

-3 - 18 = - 21 

( - 7 ) . ( - 5 ) =  35

5 + ( - 11 ) = 6 

a)-2-13-14-19=-48

b)221+4[-40-4]=221-176=45

c)(-2)^5+32=-32+32=0

d)=93

Bài 2:Tim x, biết

a)-3x=-7-8<=>x=5

b)(x-6).(7-x)=0

=>_x-6=0=>x=6

_7-x=0=>x=7

Bài 1 .Tính 

a, (-2)-13+(-14)-19

= -15+(-14)-19

= -29-19

= -48

b,221+4[(-5).8-4]

=221+4[-40-4]

=221+4(-44)

=221+(-176)

=-45

c,(-2)³.(-2)²+32

=-8.4+32

=-32+32

=0

d,-15.12-8.(-12)

=-15.12-(-8).12

=12.[-15-(-8)]

=12.(-7)

=-84

Bài 2 .Tìm x , biết

a, -3x+8=-7

    -3x=-7-8

    -3x=-15

       x=-15:(-3)

       x=5

Vậy x=5

b, (x-6).(7-x)=0

\(\Rightarrow\orbr{\begin{cases}x-6=0\\7-x=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0+6=6\\x=7-0=7\end{cases}}\)

Vậy..............................

bài dễ như vậy mà không giải được

a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)

b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)

\(\dfrac{-5}{6}-\left(\dfrac{-3}{8}+\dfrac{1}{10}\right)\)
\(\dfrac{-5}{6}-\dfrac{-3}{8}-\dfrac{1}{10}\)
 

Ko chép đề

\(2)x-17+x=x-7\)

\(x+x-x=-7+17\)

\(x=-10\)

Vậy ....

âm 10 , nhỉ ?

nhiều quá :((

\(a,2\left(x-5\right)-3\left(x+7\right)=14\)

\(2x-10-3x-21=14\)

\(-x-31=14\)

\(-x=45\)

\(x=45\)

\(b,5\left(x-6\right)-2\left(x+3\right)=12\)

\(5x-30-2x-6=12\)

\(3x-36==12\)

\(3x=48\)

\(x=16\)

\(c,3\left(x-4\right)-\left(8-x\right)=12\)

\(3x-12-8+x=0\)

\(4x-20=0\)

\(4x=20\)

\(x=5\)

Cố nốt nha bn ! 

cảm ơn, bn nha:)))

mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???

d, \(-7\left(3x-5\right)+2\left(7x-14\right)=28\)

\(\Leftrightarrow-21x+35+14x-28=28\Leftrightarrow-7x=21\Leftrightarrow x=-3\)

e, \(5\left(3-2x\right)+5\left(x-4\right)=6-4x\)

\(\Leftrightarrow15-6x+5x-20=6-4x\Leftrightarrow-5-x=6-4x\)

\(\Leftrightarrow-11+3x=0\Leftrightarrow x=\frac{11}{3}\)

f, \(-5\left(2-x\right)+4\left(x-3\right)=10x-15\)

\(\Leftrightarrow-10+5x+4x-12=10x-15\Leftrightarrow-22+9x=10x-15\)

\(\Leftrightarrow-7-x=0\Leftrightarrow x=-7\)