Tính nhanh: a) 5/7 . 10/11 + 5/7 .14/11 - 5/7 .17/11 b) 1/3 . 4/5 + 1/3
Giải thích
a)
57⋅1011+57⋅1411−57⋅1711=571011+1411−1711=57.1=57
b)
13⋅45+13⋅115−−231=13⋅45+13⋅65+23=1345+65+23=13.2+23=43
a)
57⋅1011+57⋅1411−57⋅1711=571011+1411−1711=57.1=57
b)
13⋅45+13⋅115−−231=13⋅45+13⋅65+23=1345+65+23=13.2+23=43