\(8-12x+6x^2-x^3\)

\(=\left(2-x\right)^3\)

\(125x^3-75x^2+15x-1\)

\(=\left(5x-1\right)^3\)

\(x^2-xz-9y^2+3yz\)

\(=\left(x-3y\right)\left(x+3y\right)-z\left(x-3y\right)\)

\(=\left(x-3y\right)\left(x+3y-z\right)\)

\(x^3-x^2-5x+125\)

\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)

\(=\left(x+5\right)\left(x^2-5x+25-x\right)\)

\(=\left(x+5\right)\left(x^2-6x+25\right)\)

\(x^3+2x^2-6x-27\)

\(=x^3+5x^2+9x-3x^2-15x-27\)

\(=x\left(x^2+5x+9\right)-3\left(x^2+5x+9\right)\)

\(=\left(x-3\right)\left(x^2+5x+9\right)\)

\(12x^3+4x^2-27x-9\)

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

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

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

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

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

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

\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)

Là 00000000000000

a)(25.5-5².2):(5.2)-3
= (25.5-25.2):10-3
= 25.(5-2):10-3
= 25.3:10-3
=75:10-3=7,5-3=4,5
b)(6.5² -13⁷).2-2³.(7+3)(Sai đề)
c)2³-5³ :5² +12.2²
= 8-125:25+12.4
= 8-5+12.4=8-5+48=3+48=51
d)2.[(95+5²:5):2² +180] -2².10²
= 2.[(95+25:5):4+180]-4.100
= 2.[(95+5):4+180]-400
= 2.(100:4+180)-400
= 2. (25+180)-400
= 2. 205-400
= 410-400=10
e)2⁷.2²+5⁴:5³.24-3.2⁵
= 128+625:125.24-3.32
= 128+5.24-96
= 128+120-96
= 248-96=152
f)2.[(7-3³ :3²):2²+99]-100
=2.[(7-27:9):4+99]-100
=2.[(7-3):4+99]-100
=2. (4:4+99)-100
=2.  (1+99)-100
=2.   100-100
= 200-100
=100
Chúc Bạn Học Tốt ^_^

B = 20 + 31 + 33 + 12144

B = 12228

B=20+31+33+24.22.23

B=20+31+33+528.23

B=20+31+33+12144

B=51+33+12144

B=84+12144

B=12228

Vậy B=12228

Ta có : E = 2.4 + 4.6 + 6.8 + ..... + 98.100

=> 4E = 2.4.6 - 2.4.6 + ..... + 98.100.102

=> 4E = 98.100.102

=> E = \(\frac{\text{98.100.102}}{4}=249900\)

Câu a bạn xem lại thử đề có sai không

Xin lỗi mình viết nhầm

A = 2 + 2² + 2³ + 2⁴ + ... + 2¹⁹⁹ + 2²⁰⁰

A = ( 2 + 2² + 2³ + 2⁴ ) + ... + ( 2¹⁹⁷ + 2¹⁹⁸ + 2¹⁹⁹ + 2²⁰⁰ )

A = 2 . ( 1 + 2 + 2² + 2³ ) + ... + 2¹⁹⁷ ( 1 + 2 + 2² + 2³ )

A = 2 . 15 + ... + 2¹⁹⁷ . 15

A = ( 2 + ... + 2¹⁹⁷ ) .15 \(\Rightarrow A⋮15\)

Bạn ơi ; tách từng bài ra cho dễ làm :

1.7C-C= 7^2016-7

  C  = ( 7^2016-7 ) :6

\(C=7+7^2+7^3+.....+7^{2016}\)

\(\Rightarrow7C=7^2+7^3+7^4+...+7^{2017}\)

\(\Rightarrow7C-C=\left(7^2+7^3+.....+7^{2017}\right)-\left(7+7^2+7^3+....+7^{2016}\right)\)

\(\Rightarrow6C=2^{2017}-7\)

\(\Rightarrow C=\frac{2^{2017}-7}{6}\)

a) \(A=1.2+2.3+3.4+...+29.30\)

\(\Rightarrow3A=1.2.3+2.3.\left(4-1\right)+3.4\left(5-2\right)+...+29.30\left(31-28\right)\)

\(\Rightarrow3A=1.2.3+2.3.4-1.2.3+3.4.5-2.3.4+...+29.30.31-28.29.30\)

\(\Rightarrow3A=29.30.31\)

\(\Rightarrow A=29.30.31:3\)

\(\Rightarrow A=29.10.31\)

\(\Rightarrow A=8990\)

3A= 1.2.3+2.3.4+3.4.3 +......+ 29.30.3

3A= 1.2. ﴾3 ‐ 0﴿ + 2.3.﴾4 ‐ 1﴿ +3.4. ﴾5 ‐ 2﴿....... . 29.30. ﴾31 ‐ 28﴿

3A = ﴾1.2.3 + 2.3.4 + 3.4.5 +...... +18.20.21﴿ ‐ ﴾0.1.2 + 1.2.3 + 2.3.4 +.......+ 18.19.20﴿

3A = 29.30.31 ‐ 0.1.2

3A =26970‐0

3A= 26970

 A=26970:3

A = 8990.

Vậy A=8990