a) 47 x 9 = 47 x (10 -1)

= 47 x 10 - 47 x 1 = 470 -47 = 423

24 x 99 = 24 x ( 100 -1)

= 24 x 100 - 24 x 1 = 2400 - 24 = 2376

b) 138 x 9 = 138 x (10 -1)

= 138 x 10 - 138 x 1 = 1380 - 138 = 1242

123 x 99 = 123 x (100 -1)

= 123 x 100 - 123 x 1 = 12300 - 123 = 12177

đung hết rồi

26 + 45 x 26 + 260 + 44 x 26

= 26 x 1 + 45 x 26 + 26 x 10 + 44 x 26

= 26 x (1 + 45 + 10 + 44)

= 26 x  (46 + 10 + 44)

= 26 x (56 + 44)

= 26 x 100

= 2600

26 + 45 x 26 + 260 + 44 x 26

= 26 + 45 x 26 +26 x 10 + 44 x 26

=26.(1+45+10+44)

=26.100

=2600

#Học tốt nhé

dễ mà bằng -3480,1

A,-16+23+x=-16

<=>x=-16+16-23

<=>x=-23

B,10-2(4-3x)=-4

<=>10-8+6x=-4

<=>6x=-4-10+8

<=>6x=-6

<=>x=-1

C,-12+3(-x+7)=-18

<=>-12-3x+21=-18

<=>-3x=-18+12-21

<=>-3x=-27

<=>x=9

D,24:(3x-2)=-3

<=>24/(3x-2)=-3

<=>-3(3x-2)=24

<=>3x-2=-8

<=>3x=-6

<=>x=-2

E,|x+8|-7=8

<=>|x+8|=15

<=>x+8=+-15

Chia 2 TH:

TH1:x+8=15

<=>x=7

TH2:x+8=-15

<=>x=-23

F,-45:5(-3-2x)=3

<=>-9(-3-2x)=3

<=>27+18x=3

<=>18x=-24

<=>x=-4/3

G,|x-1|=0

<=>x-1=0

<=>x=1

H,-13|x|=-26

<=>|x|=2

<=>x=+-2

a) -16 + 23 + x = -16

x = -16 + 16 - 23

x = -23

Vậy x = -23

b) 10 - 2. (4 - 3x) = -4

10 - 2 . 4 + 2. 3x = -4

10 - 8 + 6x = -4

6x = -4 - 10 + 8

6x = -6

x = (-6) : 6

x = -1

Vậy x = -1

c) -12 + 3. (-x + 7) = -18

-12 + 3. (-x) + 3. 7 = -18

-12 + (-3x) + 21 = -18

-3x = -18 + 12 - 21

-3x = -27

x = (-27) : (-3)

x = -9

Vậy x = -9

d) 24 : (3x - 2) = -3

3x - 2 = 24 : (-3)

3x - 2 = -8

3x = -8 + 2

3x = -6

x = (-6) : 3

x = -2

Vậy x = -2

e) lx + 8l - 7 = 8

lx + 8l = 8 + 7

lx + 8l = 15

\(\Rightarrow\hept{\begin{cases}x+8=15\\x=18-5\\x=13\end{cases}hay\hept{\begin{cases}x+8=-15\\x=-15-8\\x=-23\end{cases}}}\)

Vậy \(x\in\left\{13;-23\right\}\)

f) (-45) : 5. (-3 - 2x) = 3

(-9). (-3 - 2x) = 3

(-9). (-3) + 9. 2x = 3

27 + 18x = 3

18x = 3 - 27

18x = -24

x = (-24) : 18

x =\(\frac{-4}{3}\)

Vậy x =\(\frac{-4}{3}\)

g) lx - 1l = 0

\(\Rightarrow x-1=0\)

x = 0 + 1

x = 1

Vậy x = 1

h) (-13). lxl = -26

lxl = (-26) : (-13)

lxl = 2

\(\Rightarrow x=2\)

Vậy x = 2

Chúc bạn học tốt!!!

1, 15+(20-35)

=15+(-15)

=0

2,37.24+76.37

=37(24+76)

=37.100

=3700

3,420:{30:[260-(91.5-\(2^3\).\(5^2\))]}

=420:{30:[260-(455-200)

=420:[30:(260-455+200)

=420:(30:5)

=420:6

=70

5,2(x-11):3=56

<=>2(x-11)=56.3

<=>2(x-11)=168

<=>x-11=168:2

<=>x-11=84

<=>x=84+11

<=>x=95

Vậy x=95

1, -16 + 23 + x = -16

=> x = -16 + 16 - 23

=> x = -23

2.  2x - 35 = 15

=> 2x = 15 + 35

=>2x = 50

=>x = 25

3. 3x + 17 = 12

=> 3x = 12 - 17

=> 3x = -5

=> x = -5/3

4.   /x - 1 / = 0

=> x - 1 = 0

=> x = 1

5... - 13 /x/ = -26

=>/x/ = -26 : -13

=> /x/ = 2

=> x = -2 hoặc 2

1,-16+23+x=-16

23+x=-16-16

23+x=-32

x=-32-23

x=-55

2, 2x-35=15

2x=15+35

2x=50

x=50:2

x=25

3,3x+17=12

3x=12-17

3x=-5

x=-5:3

x=\(-\frac{5}{3}\)

4,|x-1|=0

x-1=0

x=0+1

x=1

5,-13.|x|=-26

|x|=-26:(-13)

|x|=2

xE{-2;2}

vậy.......

(2xX+14)+65x4=(20+140):10+260

2xX +14=(20+140):10+260:4-65

2xX=(20+140):10+260:4-65 -14

2xX=2+14+65-65-14

2xX=(14-14)+(65-65)+2

2xX=2

x=1

hợp lí nhất rùi đóa :)))))

(2.x+14)+ 65.4=(20+140) :10+260

(2X+14)+ 260 = 276

2X+14           =276-260

2X+14           =16

2X                =16-14

2X                = 2

X                  =2:2

X                   =1

26 + 45 x 26 + 260 + 44 x 26

= 26 + 45 x 26 + 26 x 10 + 44 x 26

= 26 x ( 1 + 45 + 10 + 44)

= 26 x 100

= 2600

26+45*26+260+44*26

=26*1+45*26+26*10+44*26

=26*(1+45+44+10)

=26*100

=2600

             hok tốt

                          Happy New Year mama cho con tk đi

15,6 x 260 - 156 x 26=0

15,6 x 3,3 x 3,4 x 2,6= 455,0832

=15,6 x10 x26 -156 x 26 / 15,6 x 3,3 x 3,4 x 2,6

=156 x 26 - 156 x 26 / 

=0 / 15,6 x 3,3 x 3,4 x 2,6

=0

bài 11

a) \(x^2-xy+x\\ =x\left(x-y+1\right)\)

b)

\(x^2-2xy-4+y^2\\ =\left(x^2-2xy+y^2\right)-4\\ =\left(x-y\right)^2-4\\ =\left(x-y-2\right)\left(x-y+2\right)\)

c)

\(x^3-x^2-16x+16\\ =x^2\left(x-1\right)-16\left(x-1\right)\\ =\left(x-1\right)\left(x-4\right)\left(x+4\right)\)

bài 12

\(2x\left(x-5\right)-x\left(3+2x\right)=26\)

\(2x^2-10x-3x-2x^2=26\)

\(-13x=26\\ x=-2\)

b)

\(2\left(x+5\right)-x^2-5x=0\\ 2\left(x+5\right)-x\left(x+5\right)=0\\ \left(x+5\right)\left(2-x\right)=0\\ \left[{}\begin{matrix}x+5=0\\2-x=0\end{matrix}\right.\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)