先去括号,再合并同类项,急,🈶好评

先去括号,再合并同类项,急,🈶好评
先去括号,再合并同类项,急,🈶好评
 

先去括号,再合并同类项,急,🈶好评
=7a²b-7ab-2a²b+6ab
=5a²b-ab

=7a^2b-7ab-2a^2b+6ab
=(7-2)*a^2b-(7-6)*ab
=5a^2b-ab
=ab（5a-1）

=7a^2b-7ab-2a^2b+6ab
=(7-2)*a^2b-(7-6)*ab
=5a^b-ab