5a-4(a+3b)+2b和-2(mn-ab)+2(mn-ab)怎么解

更新时间2018-07-13 11:42:28

1.  5a-4(a+3b)+2b

     =5a-4a-12b+2b

      =a-10b

2.  -2(mn-ab)+2(mn-ab)

     =-2mn+2ab+2mn-2ab

     =-2mn+2mn-2ab+2ab

     =0+0

     =0

   计算完毕  ok

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5a-4（a+3b）+2b

=5a-4a-12b+2b

=a-10b

-2(mn-ab)+2(mn-ab)

=-2mn+2ab+2mn-2ab

=0

5A-4(A+3B)+2B

=5A-4A-12AB+2B

=A-12AB+2B

-2(mn-ab)+2(mn-ab)

=2(mn-ab)-2(mn-ab)

=0

5A-4A-12B+2B=A-10B;   -2MN+2AB+2MN-2AB=0

前面等于a-10b，后面等于0