Question

去括号法则的例题

Answer 1

例1:先去括号,再合并同类项
(1) 5a-(2a-4b) ;
(2) 2x2+3(2x-2)
(3) 4+7(2x+8x)
解:(1)5a-(2a-4b)
=5a-2a+4b
=3a+4b
(2)2x2+3(2x-2)
=2x2+6x-3x2
= -2+6x
000000
-(x2-y2)+(-4x2-1)-(x2+y2)
解：=-x2+y2-x8-1-x2-y2
00000
2(5a2-2ab)-3(3a^2+4ab-b^2)
解：=20a-4ab-9a^2-12ab+3b^2
=20a-16ab-9a^2+3b^2
计算:4xy-3x2y-{3x2y+xy2-
[2xy2-4x2y+(x2y-2xy2)]}
化简
(a2-b2)-2(3a2-2b2)
(8x-3y)-(4x+3y-z)+2z
2m-3n+[5m-(3m-n)]
-(2a-b)-{b-[a-(2a-b)]}
已知m-n=3,
求4(m-n)-3m+3n+5的值
a+(b+c)=a+b+c或a+(b-c)=a+b-c
a-(b-c)=a-b+c或a-(b+c)=a-b-c