=39
过程如下:
∵m+n=6,mn=3
∴(4mn+4m+7n)+(6m-7mn) -(4mn-3n)
=4mn+4m+7n+6m-7mn -4mn+3n
=-7mn+10m+10n
=-7mn+10(m+n)
=-7x3+10x6
=-21+60
=39
(4mn+4m+7n)+(6m-7mn) -(4mn-3n)
=4mn+4m+7n+6m-7mn-4mn+3n
=10m-7mn+10n
=10(m+n)-7mn
=10*6-7*3
=60-21
=39
(4mn+4m+7n)+(6m-7mn) -(4mn-3n)
=4mn+4m+7n+6m-7mn -4mn+3n
=10m-7mn+10n
=10(m+n)-7mn
=10*6-7*3=39