Question

x² - 1 -2xy +2y
( x + 3 )²  - ( 2x - 5 ) x ( x + 3 )
( 3x + 2 )² + ( 3x -2 )² -2 ( 9x² - 4 )

Answer 1

`x^2 -1-2xy+2y`

`=(x^2-1)-(2xy-2y)`

`=(x-1)(x+1)-2y(x-1)`

`=(x-1)(x+1-2y)`

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`(x+3)^2-(2x-5)(x+3)`

`=(x+3)(x+3-2x+5)`

`=(x+3)(-x+8)`

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`(3x+2)^2 +(3x-2)^2-2(9x^2-4)`

`= (3x+2)^2 +(3x-2)^2-2(3x-2)(3x+2)`

`= (3x+2)^2-2(3x-2)(3x+2)+(3x-2)^2`

`=[(3x+2)-(3x-2)]^2`

`=(3x+2-3x+2)^2`

`= 4^2=16`

Answer 2

câu hỏi là gì vậy bạn 

Answer 3

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

 

\(\left(x+3\right)^2-\left(2x-5\right)\left(x+3\right)\\ =\left(x+3\right)\left(x+3-2x+5\right)\\ =\left(x+3\right)\left(8-x\right)\)

\(\left(3x+2\right)^2+\left(3x-2\right)^2-2\left(9x^2-4\right)\\ =9x^2+12x+4+9x^2-12x+4-18x^2+8\\ =4+4+8\\ =16\)