(2x - 7) + 17 = 6

=> 2x - 7 = 6 - 17

=> 2x - 7 = -11

=> 2x = -11 + 7

=> 2x = -4

=> x = -4 : 2

=> x = -2

+) 12 -2(3 - 3x)= -2

=> 2(3 - 3x) = 12 + 2

=> 2(3 - 3x) = 14

=> 3 - 3x = 14 : 2

=> 3 - 3x = 7

=> 3x = 3 - 7

=> 3x = -4

=> x = -4/3

\(\left(x+1\right)\left(x-3\right)=0\)

=> \(\orbr{\begin{cases}x+1=0\\x-3=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=-1\\x=3\end{cases}}\)

Vậy...

=(1+98-99-100)+(2-3-4+5)+(6-7-8+9)+...+(95-96-97+98)

=-100+0+0+0+0+0.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................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x-32+15-3x=-4x+1-32

x-3x+4x=1-32+32-15

2x=1+32-32-15

2x=1+(32-32)-15

2x=1-15

2x=-14

x=-14:2

x= - 7

a, (- 40 - 16 + 32 ) + ( 40 + 116 - 32 )

=( - 40 )- 16 + 32 + 40 + 116 - 32

=[(-40)+40]+32-32+116-16

=0+ (32-32)+(116-16)

=0+0+100

=100

b, -15 + 5 + ( 20 - 100 - 2017 ) - ( - 15 - 2017 )

=  -15 + 5 + 20 - 100 - 2017 + 15 + 2017 

=[(-15 )+ 15] + (2017 - 2017 ) + 20-100

=0+0+(20-100)

= - 80

a,\(2x+12-18=x+4-18\)

\(\Rightarrow2x-x=4-1+18-12\)

\(\Rightarrow x=9\)

b,\(-5x+10-102=-6x-102\)

\(\Rightarrow-5x+6x=-102+102-10\)

\(\Rightarrow x=-10\)

a, 2x + 12 - 18 = x + 4 - 18

    2x -x           = 4 - 18 - 12 + 18

     x               =  - 8

b, - 5x + 10 - 102 = - 6x - 102

    - 5x + 6x         = -102 - 10 + 102

        x                = - 10

VERY GOOD!!!

nhanh ho minh voi

Phan h moi so ra TSNT roi nhan len la ra!!

a,ta co:

\(220=2^2.5.11\)

\(240=2^4.3.5\)

\(300=2.3.5^2\)

\(\Rightarrow UCLN\left(220,240,300\right)=2.3.5=30\)

\(BCNN\left(220,240,300\right)=2^4.3.5^2=1200\)

Cac cau con lai tuong tu nha!!

HTDT

a ) Ta có : \(220=2^2\cdot5\cdot11\)

                 \(240=2^4\cdot3\cdot5\)

                 \(300=2^2\cdot3\cdot5^2\)

\(\Rightarrow\:ƯCLN\)\(\left(220;240;300\right)=2^2\cdot5=20\)

\(\Rightarrow BCNN\left(220;240;300\right)=2^4\cdot3\cdot5^2\cdot11=13200\)

b)  Ta có : \(40=2^3\cdot5\)

                \(75=3\cdot5^2\)

                \(105=3\cdot5\cdot7\)

\(\RightarrowƯCLN\left(40;75;105\right)=5\)

\(\Rightarrow BCNN\left(40;75;105\right)=2^3\cdot3\cdot5^2\cdot7=4200\)

c) 

\(C1:\) Ta có : \(18=2\cdot3^2\)

                 \(36=2^2\cdot3^2\)

                \(72=2^3\cdot3^2\)

\(\Rightarrow\:\)\(ƯCLN\)\(\left(18;36;72\right)=2\cdot3^2\)\(=18\)

\(\Rightarrow BCNN\left(18;36;72\right)=2^3\cdot3^2=72\)

\(C2:\)  Vì      \(36⋮18;72⋮18;18⋮18\)      nên \(\:ƯCLN\)\(\left(18;36;72\right)=18\)

              Vì      \(72\)  chia hết cho \(18;36;72\) nên \(BCNN\left(18;36;72\right)=72\)

\(A=\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{870}\)

\(A=\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+...+\frac{1}{29\cdot30}\)

\(A=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{29}-\frac{1}{30}\)

\(A=\frac{1}{3}-\frac{1}{30}\)

\(A=\frac{3}{10}\)

\(A=\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+..........+\frac{1}{870}\)

\(=\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+................+\frac{1}{29.30}\)

\(=\frac{1}{3}-\frac{1}{30}\)

\(=\frac{9}{30}=\frac{3}{10}\)