itande
幼苗
共回答了2个问题 举报
已知A=2a+3,B=-4a^2+3a-1,C=3a^2-4a+4,求4A+{2B-[5A-(3B-2C)+6B]+3C}的值
这是原题阿.
4A+{2B-[5A-(3B-2C+6B]+3C}=4A+[2B-(5A-3B+2C-6B+3C)]=4A+2B-5A+3B-2C+6B-3C
=-A+11B-5C
代入ABC
原式=-(2a+3)+11(-4a2+3a-1)-5(3a2-4a+4)=-2a-3+(-44a2+33a-11)-(15a2-20a+20)
=-2a-3-44a2+33a-11-15a2+20a-20=-59a^2-51a-34
1年前
2