1、去括号:(1)a+(b+c-d)= (a+b+c-d),a-(b+c-d)=(a-b-c+d);(2)a+5(b+2c-3d)=(a+5b+10c-15d),a-m(b+2c-3d)=(a-mb-2mc+3md)。2、添括号:(1)-3p+3q-1=+(-3p+3q-1)=3p-(3q+1)(2)(a-b+c-d)(a+b-c+d)=【a-(b--c+d)】{a+(b-c+d)}3、去括号且合并含相同字母的项:(1)3+(2x-y)-(y-x)=(3+2x-y-y+x=3+3x-2y;(2)2x-5a-(7x-2a)=(2x-5a-7x+2a=-5x-3a(3)a-2(a+b)+3(a-4b)=(2a-14b(4)x+2(3-x)-3(4x-1)=(-13x+9(5)2x-(5a-7x-2a)=(9x-3d(6)2(x-3)-(-x+4)=(3x-104、(1)已知b<a<0,且|a|>c>0,则代数式|a|-|a+b|+|c-d|+|a+c|化简的结果是(-a-{-(a+b)】+c-d-(a+c)=-2b-a (2)不改变值,将括号前的符号变成与其相反的符号:①x+(1-x�0�5+x�0�6)=(x-(x^2-x^3-1)②(x-y)-(-y+x-1)=(x-y)+(y-x+1));(此题第一个小括号前的符号不要求改变)③3x-【5x-(2x-1)】=(3x+{(2x-1)-5x}