DearEDU. com 例1.计算:(x+2y)2 解:(x+2y)2x2+2x2y+2y2 =x2+4xy+4y2
例1.计算: (x+2y)2 解: (x+2y)2= ( a+ b)2=a2+2 a b+ b2 =x2+4xy+4y2 x 2+2·x·2y+(2y)2
利用和的完全平方公式计算 (1)(a+1)2=()2+2()()+()2 (2)(2a+3b)2=()2+2()()+()2 (3)(-4x+5y)2=()2+2()()+()2
(1) (a+1 )2 = ( )2 +2( )( )+ ( )2 (3) (-4x+5y)2 =( )2 +2( )( )+ ( )2 = (2) (2a+3b ) 2 = ( )2 +2( )( )+ ( )2 利用和的完全平方公式计算: = =