(2x-3)^2-(2x-5)^2 (rút gọn biểu thức)

`C_1 :`

       `( 2x - 3 )² - ( 2x - 5 )²`

`= [ ( 2x )² - 2.2x.3 + 3² ] - [ ( 2x )² - 2.2x.5 + 5² ]`

`= ( 4x² - 12x + 9 ) - ( 4x² - 20x + 25 )`

`= 4x² - 12x + 9 - 4x² + 20x - 25`

`= ( 4x² - 4x² ) - ( 12x - 20x ) + ( 9 - 25 )`

`= -( -8x ) + ( -16 )`

`= 8x - 16`

`C_2 :`

       `( 2x - 3 )² - ( 2x - 5 )²`

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

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

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

`= 2( 4x - 8 )`

`=2.4x - 2.8`

`= 8x - 16`

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`@  \text{Tips}`

`( A + B )² = A² + 2AB + B²`

`A² - B² = ( A - B )( A + B )`

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