Question

A = ( 5x - 1 ) ( 5x + 1 ) - ( x - 2 ) ( x² + 2x + 4 )

A = ( x - 2 )² - ( x - 1 ) ( x + 1 ) - ( 2x + 3 )²

A  =  ( x +2 )³  - ( x - 1 )³  - ( 2x + 3 ) ( 4x² - 6x + 9 )

 

Answer 1

A = ( 5x - 1 ) ( 5x + 1 ) - ( x - 2 ) ( x² + 2x + 4 )

giải:

\(A=\left(5x\right)^2-1-\left(x^3-2^3\right)=25x^2-1-x^3+8=-x^3+25x^2+7\)

A = ( x - 2 )² - ( x - 1 ) ( x + 1 ) - ( 2x + 3 )²

giải:

\(A=x^2-4x+4-\left(x^2-1\right)-\left[\left(2x\right)^2+12x+9\right]\)

\(A=x^2-4x+4-x^2+1-4x^2-12x-9\)

\(A=-4x^2-16x-4\)

A  =  ( x +2 )³  - ( x - 1 )³  - ( 2x + 3 ) ( 4x² - 6x + 9 )

giải:\(A=x^3+3x^2.2+3x.2^2+2^3-\left(x^3-3x^2.1+3x.1^2-1^3\right)-\left(8x^3-12x^2+18x+12x^2-18x+27\right)\)\(A=x^3+6x^2+12x+8-x^3+3x^2-3x^2+1-8x^3+12x^2-18x-12x^2+18x-27\)\(A=-8x^3+9x^2-18\)