早教吧 育儿知识 作业答案 考试题库 百科 知识分享

因式分解:①(a+3)(a-7)+25②81a4+16b4-72a2b2

题目详情
因式分解:
①(a+3)(a-7)+25
②81a4+16b4-72a2b2
▼优质解答
答案和解析
①(a+3)(a-7)+25,
=a2-4a-21+25,
=a2-4a+4,
=(a-2)2
②81a4+16b4-72a2b2
=(9a2-4b22
=(3a+2b)2(3a-2b)2