8:

a: \(27\left(1-x\right)\left(x^2+x+1\right)+81x\left(x-1\right)\)

\(=27\left(1-x^3\right)+81x^2-81x\)

\(=27-27x^3+81x^2-81x\)

b: \(y\left\lbrack x^2+x\left(x-y\right)+\left(x-y\right)^2\right\rbrack+\left(x-y\right)^3\)

\(=x^2y+xy\left(x-y\right)+y\left(x^2-2xy+y^2\right)+x^3-3x^2y+3xy^2-y^3\)

\(=x^3-2x^2y+3xy^2-y^3+x^2y-xy^2+x^2y-2xy^2+y^3\)

=x^3

9:

a: \(A=3\left(x-1\right)^2-\left(x+1\right)^2+2\left(x-3\right)\left(x+3\right)-\left(2x+3\right)^2-\left(5-20x\right)\)

\(=3\left(x^2-2x+1\right)-x^2-2x-1+2\left(x^2-9\right)-\left(4x^2+12x+9\right)-5+20x\)

\(=3x^2-6x+3-x^2+18x-6+2x^2-18-4x^2-12x-9\)

=3-6-18-9

=-3-18-9

=-3-27

=-30

b: \(B=-x\left(x+2\right)^2+\left(2x+1\right)^2+\left(x+3\right)\left(x^2-3x+9\right)-1\)

\(=-x\left(x^2+4x+4\right)+4x^2+4x+1+x^3+27-1\)

\(=-x^3-4x^2-4x+x^3+4x^2+4x+27=27\)

1)...=135+65+360+40+24=200+400+24=624

2)...=(8.125).(4.25)=1000.100=100000

4)...= (467+433)+(238+762)+3465=990+1000+3465=5455

5)...=129.(172-73+1)=129.100=12900

6)...=205-(1200-(16-6)³):40=205-(1200-1000):40=205-200:40=205-5=200

Trả lời chi tiết giúp mình đc ko

Gọi 3 phần dc chia thành là x,y,z

=> 2x =3y =4z ; x+y+z =52

\(\frac{x}{\frac{1}{2}}=\frac{y}{\frac{1}{3}}=\frac{z}{\frac{1}{4}}=\frac{x+y+z}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}}=\frac{52}{\frac{13}{12}}=48\)

=>.x = 48.1/2 =24

=>y =48.1/3 =16

=>z = 48.1/4 =12

Câu A nha em

xót xa, đường sá

\(205\left[1200-\left(4^2-2.3\right)^3\right]:40\)

\(=205\left[1200-\left(16-6\right)^3\right]:40\)

\(=205\left[1200-10^3\right]:40\)

\(=205\left[1200-1000\right]:40\)

\(=205.200:40\)

\(=205.5\)

\(=1025\)

Ủng hộ nha

205[1200-(4²-2.3)³]:40

=205[1200-10³]:40

=205.200:40

=1025

205 - [ 1200 - ( 4² - 2 . 3 )³ ] : 40

= 205 - [ 1200 - ( 16 - 2 . 3 )³ ] : 40

= 205 - [ 1200 - ( 16 - 6 )³ ] : 40

= 205 - [ 1200 - 10³ ] : 40

= 205 - [ 1200 - 1000 ] : 40

= 205 - 200 : 40

= 205 - 5

= 200

ai h minh minh h lai cho