如题所述
第1个回答 2021-08-05
72x79
=(80-1)x72
=80x72-72
=5760-72
=5688
=(80-1)x72
=80x72-72
=5760-72
=5688
第2个回答 2021-08-04
72×79
=72×(80-1)
=72×80-72×1
=5760-72
=5700-72+60
=5628+60
=5688
=72×(80-1)
=72×80-72×1
=5760-72
=5700-72+60
=5628+60
=5688
第3个回答 2021-08-04
=72×(80-1)
=(70+2)×(80-1)
=70×80-70+2×80-2×1
=5600-70+160-2
=(5600+160-70)-2
=(5760-70)-2
=5690-2
=5688
=(70+2)×(80-1)
=70×80-70+2×80-2×1
=5600-70+160-2
=(5600+160-70)-2
=(5760-70)-2
=5690-2
=5688
第4个回答 2021-08-05
72×79
=72×(80-1)
=72×80-72
=5760-72
=5688
=72×(80-1)
=72×80-72
=5760-72
=5688
第5个回答 2021-08-04
(70+2)*(80-1)=5600-70+160-2=5688