七年级数学去括号的试题要有答案的
去括号前面是加号的，打开括号，符号不变。如果是减号，要变号。8x-(-3x-5)
=8x+3x+5=11x+5
(3x-1)+(2-5x)
=3x-1+2-5x=1-2x
(-4y+3)-(-5y-2)=-4y+3+5y+2=y+5
3x+1-2(4-x)=3x+1-8+2x=5x-7
式子-{-[a-(b-c)]}去括号应为
A
a+b+c
B
a-b+c
C
-a+b-c
D.
a-b-c
答案:B
m、n互为相反数，则(3m-2n)-(2m-3n)=?
答案:原式=m+n=0
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