d) 12x 156 - 12 x 55 - 12

= 12 x ( 156 - 55 - 12 )

= 12 x 100

= 1200

e ) 12 x 11 + 21 x 11 + 11 x 33

= ( 12+ 21 + 33) x 12

= 66 x 11

= 726

g) 132 x 11 - 11 x 32 - 54 x 11

= ( 132 - 32 - 54 ) x 11

= 46 x 11

= 506

d) 12 x 156 - 12 x 55 - 12 = 12x(156 - 55 - 1 ) = 12 x 100 = 1200

e) 12 x 11 + 21 x 11 + 11 x 33 = 11  x ( 12 + 21 + 33 ) = 11  x 66 = 726

g) 132 x 11 - 11 x 32 - 54 x 11 = 11 x ( 132 - 32 - 54 ) = 11 x 46 = 506

d) \(12\times156-12\times55-12\) \(=12\times\left(156-55-1\right)\)

                                                         \(=12\times100=1200\)

e) \(12\times11+21\times11+11\times33\)\(=11\times\left(12+21+33\right)=11\times66=726\)

g) \(132\times11-11\times32-54\times11\) \(=11\times\left(132-32-54\right)=11\times46=506\)

13/19x23/11-13/19x8/11-13/19x4/11

=(23/11-8/11-4/11)=11/11=1

=13/19x1

=13/19

13/19 x 23/11 - 13/19 x 8/11 - 13/19 x 4/11

= 13/19 x (23/11 - 8/11 - 4/11)

= 13/19 x 1

= 13/19

\(\dfrac{13}{19}\times\dfrac{23}{11}-\dfrac{13}{19}\times\dfrac{8}{11}-\dfrac{13}{19}\times\dfrac{4}{11}\\ =\dfrac{13}{19}\times\left(\dfrac{23}{11}-\dfrac{8}{11}-\dfrac{4}{11}\right)\\ =\dfrac{13}{19}\times1=\dfrac{13}{19}\)

câu b, 20/5x7 + 20/7x9 + 20/ 9 x11 + ..... 20 / 33 x35

 a)12 x 11 + 21 x 11 x 11 + 11 x 33

= ( 12 x 11 ) + ( 21 x 11 x 11 ) + ( 11 x 33 )

= 

= 

b)132x11-11x32-54x11

= ( 132 x 11 ) - ( 11 x 32 ) - ( 54 x 11 )

= 

\(a,=11\times\left(12+21+33\right)=11\times66=726\\ b,=11\times\left(132-32-54\right)=11\times46=506\\ c,=11\times\left(245+365\right)=11\times610=6710\\ d,=75\times\left(78+89+123\right)=75\times290=21750\\ e,=\left(2\times50\right)\times\left(250\times8\right)=100\times2000=200000\\ g,=1994\times\left(867+11\right)=1994\times878=1750732\)

a) 12 x 11 + 21 x 11 + 11 x 33

= 11 x ( 12 + 21 + 33)

= 11 x 66

= 726

b) 132 x 11 - 11 x 32 - 54 x 11

= 11 x ( 132 - 32 - 54)

= 11 x 46

= 506

c) 245 x 11 + 11 x 365

= 11 x ( 245 + 365 )

= 11 x 610 = 6710

d) 78 x 75 + 75 x 89 + 75 x 123

= 75 x ( 78 + 89 + 123)

= 75 x 290 = 21750

e) 2 x 250 x 50 x 8

= (2 x 50) x ( 250 x 8)

= 100 x 2000 = 200000

g) 1994 x 867 + 1994 x 11

= 1994 x ( 867 + 11)

= 1994 x 878 = 1750732

nhiều thế

sfdhg 

- 135

Tick minh nhe !

135 tick nhé Huỳnh Thị Mỹ Duyên

x=-2 nha bạn Cá là có trong violympic

\(\Rightarrow\frac{x+2}{10^{10}}+\frac{x+2}{11^{11}}-\frac{x+2}{12^{12}}-\frac{x+2}{13^{13}}=0\)

\(\Rightarrow\left(x+2\right)\left(\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}\right)=0\)

Vì \(\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}\ne0\)

=>x+2=0

=>x=-2

Vậy x=-2

=>

\(\frac{x+2}{10^{10}}+\frac{x+2}{11^{11}}-\frac{x+2}{12^{12}}-\frac{x+2}{13^{13}}=0\)

=>\(\left(x+2\right).\left(\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}=0\right)\)

vì \(\frac{1}{10^{10}}>\frac{1}{11^{11}}>\frac{1}{12^{12}}>\frac{1}{13^{13}}=>\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}\ne0\)

=>x+2=0

=>x=-2

tick nhé

\(\frac{x+2}{10^{10}}+\frac{x+2}{11^{11}}=\frac{x+2}{12^{12}}+\frac{x+2}{13^{13}}\)

\(=>\frac{x+2}{10^{10}}+\frac{x+2}{11^{11}}-\frac{x+2}{12^{12}}-\frac{x+2}{13^{13}}=0\)

\(=>\left(x+2\right).\left(\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}\right)=0\)

Vì \(\frac{1}{10^{10}}>\frac{1}{11^{11}}>\frac{1}{12^{12}}>\frac{1}{13^{13}}\)

Nên \(\frac{1}{10^{10}}+\frac{1}{11^{11}}-\frac{1}{12^{12}}-\frac{1}{13^{13}}\)khác 0

Suy ra:  x+2=0

             x   =0 - 2

             x = -2

                              TICK NHA