Tính nhanh a) 5/13 + -5/7 + -20/41 + 8/13 + -21/41 b) 1/28 + -1/14
Giải thích
a) 513+−57+−2041+813+−2141=513+813+−2041+−2141+−57=−57
b) 128+−114+328+−17+314=128+328+−114+314+−17=17
c) 12+−23+34+−45+56+−56+45+−34+23+−12=12+−12+34+−34+−45+45+56+−56=0
a) 513+−57+−2041+813+−2141=513+813+−2041+−2141+−57=−57
b) 128+−114+328+−17+314=128+328+−114+314+−17=17
c) 12+−23+34+−45+56+−56+45+−34+23+−12=12+−12+34+−34+−45+45+56+−56=0