1、AAAAA=A11111 A0A0A0A0A=A101010101ABABABABAB=AB101010101 ABCABCABC=ABC10010011234567654321=111111111111112. 常见公式=- 如:= - =( - ) 如:=( - ) =( - )= + = + (a,b不等于0)即:= + 如:= + = + 3. 字母代替法在多个代数式运算时,可以设最短的算式为a,次短的算式为b典型考题:分析 1234567654321=11111111111111,所以约分后= = + + + = + + + = 1( + + + )( 1+ + ) ( 1+ + +
2、 + )( + + )解:设 + + = m,+ + + = n,所以原式= n(1 + m)- (1 + n) m =n + mn - m mn =n m =+ + + - ( + + ) = + + + + + = (1- )+ ( - )+ ( - )+ +( - )= 1- = 2+ 4+ 6+ 8根据:原式=(2+4+6+8)+(1- +-+-+- ) =20+(1- ) =20已知A= 1- + - + - + + - ,B= + + + + + ,则A B,它们相差 。A= 1- + - + - + + - = 1+ + + + + + + + -2( + + + + ) =1+ + + + + + + + -( 1+ + + + + ) =+ + + + + 所以B A, BA=- =