早教吧 育儿知识 作业答案 考试题库 百科 知识分享

计算:(1)(8xy-x2+y2)-(x2-y2+8xy)(2)3a2-[7a-(4a-3)-2a2]+3.

题目详情
计算:
(1)(8xy-x2+y2)-(x2-y2+8xy)
(2)3a2-[7a-(4a-3)-2a2]+3.
▼优质解答
答案和解析
(1)原式=8xy-x2+y2-x2+y2-8xy=-2x2+2y2
(2)原式=3a2-(7a-4a+3-2a2)+3=3a2-3a-3+2a2+3=5a2-3a.