Jawabanmu

2014-08-13T19:12:27+07:00
(x + y)² = ( x+y )( x+y )
= x² + xy + xy + y²
= x² + 2xy + y²

(x - y)² = ( x-y )( x-y )
= x² - xy - xy + y²
= x² - 2xy + y²