先化简再求值(初二上册)

1.已知x+y=5,2x-y=1化简xy(x+y的平方

2.-y的平方(xy-x)+2x(x-y的平方),并求它们的值。

3.3.3ab-4ab+8ab-7ab+ab=______

4.7x-(5x-5y)-y=______

523a3bc2-15ab2c+8abc-24a3bc2-8abc=______

6-7x2+6x+13x2-4x-5x2=______

72y+(-2y+5)-(3y+2)______11(2x2-3xy+4y2)+(x2+2xy-3y2)=______ 122a-(3a-2b+2)+(3a-4b-1)=______13-6x2-7x2+15x2-2x2______ 142x-(x+3y)-(-x-y)-(x-y)______162x+2y-[3x-2(x-y)]=______ 175-(1-x)-1-(x-1)=______18( )+(4xy+7x2-y2)=10x2-xy 19(4xy2-2x2y)-( )=x3-2x2y+4xy2+y321已知A=x3-2x2+x-4B=2x3-5x+3计算A+B=______22已知A=x3-2x2+x-4B=2x3-5x+3计算A-B=______23若a=-0.2b=0.5代数式-(|a2b|-|ab2|)的值为______25一个多项式减去3m4-m3-2m+5得-2m4-3m3-2m2-1那么这个多项式等于______26-(2x2-y2)-[2y2-(x2+2xy)]=______ 27若-3a3b2与5ax-1by+2是同类项则x=______y=______ 28(-y+6+3y4-y3)-(2y2-3y3+y4-7)______29化简代数式4x2-[7x2-5x-3(1-2x+x2)]的结果是______302a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( ) 313a-(2a-3b)+3(a-2b)-b=______32化简代数式x-[y-2x-(x+y)]等于______ 33[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1343x-[y-(2x+y)]=______35化简|1-x+y|-|x-y|(其中x0y0)等于______36已知x≤y x+y-|x-y|=______37已知x0y0化简|x+y|-|5-x-y|=______384a2n-an-(3an-2a2n)______39若一个多项式加上-3x2y+2x2-3xy-4得2x2y+3xy2-x2+2xy则这个多项式为______ 40-5xm-xm-(-7xm)+(-3xm)=______41当a=-1b=-2时

[a-(b-c)]-[-b-(-c-a)]______43当a=-1b=1c=-1时

-[b-2(-5a)]-(-3b+5c)______44-2(3x+z)-(-6x)+(-5y+3z)=______ 45-5an-an+1-(-7an+1)+(-3an)______463a-(2a-4b-6c)+3(-2c+2b)=______ 489a2+[7a2-2a-(-a2+3a)]=______50当2y-x=5时5(x-2y)2-3(-x+2y)-100=______