【正文】
(b+c) = _____________; (2)a – (bcd) = _____________; (3) – (ab) + (c+d) = ____________. a – b + c a – b + c + d – a + b + c + d ,在 ___上填上 “ +”號或“ ”號: (1)a ___ (b+c) = ab+c ; (2)a ___ (bcd) = ab+c+d ; (3) ___(ab) ___ (c+d) = c+da+b. + + – – :去括號 ( 1) a + 2(– b + c ) = ( 2 ) ( a – b ) – ( c + d ) = ( 3 ) – (– a + b ) – c = ( 4 ) 2x– 3( x2 – y2 ) = a – 2b + 2c a – b – c – d a – b – c 2x – 3x2 + 3y2 鞏固新知 ?如有錯誤請改正。