Question

Câu 13. (1 điểm) Khai triển mỗi hằng đẳng thức sau.

a) ${{\left( 2x+1 \right)}^{2}}$;                                                  

b) ${{\left( a-\dfrac{b}{2} \right)}^{3}}$.          

Answer 1

 

Answer 2

a)(2x+1)²=(2x²-2.2x.1+1²)
 

Answer 3

(2x+1)^2=4x^2+4x+1.

(a-b/2)^3=(a-b/2)(a^2+ab/2+b^2/4).

Answer 4

a) =   2x² + 2.2x.1 +1²

    = 2x² + 4x + 1²

b) = A³ - 3.a².b/2+3.a.b/2²-b/2³

 

Answer 5

a, (2x +1)² = 4x² + 4x + 1

b, ( a - b/2 )³ = a² - 2.a.b/2 + (b/2)²

Answer 6

a, ( 2x + 1 ) ²

^{= (2x)2 + 2 . x. 1 + 1^2}

^{= 4x^2 + 2x + 1}

Answer 7

Đỗ 

Answer 8

a) (2x + 1)²=(2x²) + 2.2x.1+ 1²

=4x²+4x+1

b)( a+ \(\dfrac{b}{2}\))³=a³+3.a².\(\dfrac{b}{2}\)+3.a.(.\(\dfrac{b}{2}\))²+(\(\dfrac{b}{2}\))³

=a³+\(\dfrac{3}{2}\)a²b+\(\dfrac{3}{4}\)ab²+\(\dfrac{b}{8}\)

(2�+1

Answer 9

a) (2x + 1)² = (2x)² +  2 . 2x . 1 + 1² = 4x² + 4x + 1

b) (a - b/2)² = (a)² - 2 . a . b/2 + (b)² = a² - ab + b²

Answer 10

a) ( 2x + 1)² = ( 2x)² + 2.2x.1 + 1²

                    = 4x² + 4x + 1 

b) ( a - b/2 ) ³ = a³ - 3. a².b/2 + 3.a.(b/2)² - (b/2)³

                      = a³ - 3/2 a^2b + 3/4 ab  - 1/8b

Answer 11

a) (2x+1)^2= 4x^2+4x+1                                     b) (a - b/2)^3 = a^3 - 3a^2b/2 - 3ab^3/8

 

 

 

 

Answer 12

a) 4x²+4x+1

b) a³-3a²\(\dfrac{b}{2}\)+3a\(\dfrac{b^2}{4}\)-\(\dfrac{b^3}{8}\)

Answer 13

 

Answer 14

) (2�+1)2=4�2+4�+1(2x+1)2=4x2+4x+1.

b) (�−�2)3=�3−3�2.�2+3�(�2)2−(�2)3(a−2b​)3=a3−3a2.2b​+3a(2b​)2−(2b​)3

=�3−32�2�+34��2−18�3=a3−23​a2b+43​ab2−81​b3.

Answer 15

Answer 16

a) (2�+1)2=4�2+4�+1(2x+1)2=4x2+4x+1.

b) (�−�2)3=�3−3�2.�2+3�(�2)2−(�2)3(a−2b​)3=a3−3a2.2b​+3a(2b​)2−(2b​)3

=�3−32�2�+34��2−18�3=a3−23​a2b+43​ab2−81​b3

Answer 17

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Answer 22

 

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Answer 24

 

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Answer 28

 

Answer 29

a) (2x+1)^2=4x^2 +4x +1

b) (a-b/2)^3=a^3 -3/2a^2b+3/4ab^2-1/8b^3

Answer 30