先去括号,在合并同类项2分之1x-(2分之1x+3分之1y²)-2(x+3分之1y²)2.在下面各题
先去括号,在合并同类项
2分之1x-(2分之1x+3分之1y²)-2(x+3分之1y²)
2.在下面各题等号后面的括号内填上适当的项
(1)(a+b+c)(a-b-c) (2)(a-b+c)(a+b-c)
=[a+( )][a-( )] = [a-( )][a+( )]
(3)(-a+b+c)(a+b-c) (4)(a+b-c-d)(a-b+c-d)
=[b-( )][b+( )] = [(a-d)+( )][(a-d)-( )]
(5)-4m+6n (6)3x³-2x²-6x+4
=-2( ) =(3x³-2x²)-( )
(7)m²-mx-n²-nx (8)m²-n²+2n-1
=(m²-n²)-( ) =m²-( )
(9)2ab+1-a²-b²
=1-( )