七年级数学去括号练习题.doc

去括号、添括号1归纳出去括号的法则吗?:(1)a+(-b+c-d);(2)a-(-b+c-d);(3)-(p+q)+(m-n);(4)(r+s)-(p-q).?若有错,请改正:(1)a2-(2a-b+c)(2)-(x-y)+(xy-1)=a2-2a-b+c;=-x-y+xy-1.(3)(y-x)2=(x-y)2(4)(-y-x)2=(x+y)2(5)(y-x)3=(x-y):(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)。,在___上填上“+”号或“-”号:(1)a___(-b+c)=a-b+c;(2)a___(b-c-d)=a-b+c+d;(3)___(a-b)___(c+d)=c+d-a++y=2,则x+y+3= ,5-x-y= .:(1)a+3(2b+c-d); (2)3x-2(3y+2z).(3)3a+4b-(2b+4a); (4)(2x-3y)-3(4x-2y).(1)2a-3b+[4a-(3a-b)];(2)3b-2c-[-4a+(c+3b)]+-[2(x+3y)-3(x-2y)]的结果是().+2; -12y+2; C.-5x+12y+2; -(1),与a-b-c的值不相等的是()-(b+c)-(b-c)C.(a-b)+(-c)D.(-c)+(-b+a)-[0-(2p-q)]的结果是()A.-2p-qB.-2p+-+,正确的是()-(2b-3c)=a-2b--(3x2+2x-1)=x3-3x2-2x-+(-2y+1)=2y2-2y+1D.-(2x-y)-(-x2+y2)=-2x+y+x2+:a+(b-c)=;(a-b)+(-c-d)=;-(a-b)-(-c-d)=;5x3-[3x2-(x-1)]=..(1)x-(y-z)=x-y-z()(2)-(x-y+z)=-x+y-z()(3)x-2(y-z)=x-2y+z()(4)-(