一. 去括号: (1)a+(-b+c-d); (2)a-(-b+c-d) ; (3)-(p+q)+(m-n); (4)(r+s)-(p-q); (5)x+(y-z)-(-y-z-x); (6) a+3(2b+c-d); (7)2x-3y)-3(4x-2y). 二.下列去括号有没有错误?若有
一. 去括号: (1)a+(-b+c-d); (2)a-(-b+c-d) ; (3)-(p+q)+(m-n); (4)(r+s)-(p-q); (5)x+(y-z)-(-y-z-x); (6) a+3(2b+c-d); (7)2x-3y)-3(4x-2y). 二.下列去括号有没有错误?若有错,请改正: (1)a2-(2a-b+c) =a2-2a-b+c (2)-(x-y)+(xy-1) =-x-y+xy-1 四.填空 1.根据去括号法则,在___上填上“+”号或“-”号: (1) a___(-b+c)=a-b+c; (3) ___(a-b)___(c+d)=c+d-a+b ,5-x-y= . (2)a___(b-c-d)=a-b+c+d; 2.已知 x+y=2,则x+y+3= 3. 化简 2-[2(x+3y)-3(x-2y)]的结果是. 五.化简 1 (1)(2x-3y)+(5x+4y);(2)(8a-7b)-(4a-5b);(3)a-(2a+b)+2(a-2b); (4)3(5x+4)-(3x-5); (5)(8x-3y)-(4x+3y-z)+2z; (6)-5x2+(5x-8x2)-(-12x2+4x)+2; (7)2-(1+x)+(1+x+x2-x2); (8)3a2+a2-(2a2-2a)+(3a-a2); (9)2a-3b+[4a-(3a-b)] ; (10)3b-2c-[-4a+(c+3b)]+c; (11)a-(a-3b+4c)+3(-c+2b) (12)2x2-{-3x+6+[4x2-(2x2-3x+2)]} 2 (13)4(a+b)+2(a+b)-7(a+b) (14)3(x-y)2-7(x-y)+8(x-y)2+6(x-y) (15)a>0,b>0, |6-5b|-|3a-2b|-|6b-1| (16)1