化简求值:
(1)化简:4(2x2-xy)-(x2+xy-6?)??
(2)已知A=2a2b-ab2,B=-a2b+2ab2
①求5A+4B;
②若|a+2|+(3-b)2=0,求5A+4B的值;
③试将a2b+ab2用A与B的式子表示出来.
网友回答
解:(1)原式=8x2-4xy-x2-xy+6=7x2-5xy+6;
(2)①5A+4B=5(2a2b-ab2)+4(-a2b+2ab2)=10a2b-5ab2-4a2b+8ab2=6a2b+3ab2;
②∵|a+2|+(3-b)2=0,
∴a=-2,b=3,
当a=-2,b=3时,5A+4B=18;
③a2b+ab2=A+B.
解析分析:(1)先去括号,然后合并同类项即可得出