Đáp án+Giải thích các bước giải:

`3) ( 6 - x )^2 = 36 - 12x + x^2`

`4) ( x - 5 )^2 = x^2 - 10x + 25`

`7) ( 2x - 1 )^2 = 4x^2 - 4x + 1`

`8) ( 3x - 2 )^2 = 9x^2 - 12x + 4`

`11) ( x - 2y )^2 = x^2 - 4xy + 4y^2`

`12) ( 2x - y )^2 = 4x^2 - 4xy + y^2`

`15) ( 2x - 3y )^2 = 4x^2 - 12xy + 9y^2`

`16) ( 2x - 5y )^2= 4x^2 - 20xy + 25y^2`

`19) ( x^2 - y^2 )^2= x^4 - 2x^2y^2 + y^4`

`20 ) ( 3x - y^2 )^2 = 9x^2 - 6xy^2 + y^4`

`23) ( 4x - 2y^2 )^2 = 16x^2 - 16xy^2 + 4y^4`

`24) ( 4x^2 - 2y )^2 = 16x^4 - 16x^2y + 4y^2`

Áp dụng HĐT: 

`( a - b )^2 = a^2 - 2ab + b^2`

`( a + b )^2 = a^2 + 2ab + b^2`