Tính (1/4.9 +1/ 9.14 +1/ 14.19 +...+ 1/ 44. 49) . 1 -3 -5 -7 -...- 49/ 89
Giải thích
14.9+19.14+114.19+...+144.49.1−3−5−7−...−4989
=1514−19+19−114+...+144−149.1−3+5+7+...+4989
=1514−149.1−3+49.49−3:2+1289
=15.45196.1−62489
=9196.−62389
=−928
14.9+19.14+114.19+...+144.49.1−3−5−7−...−4989
=1514−19+19−114+...+144−149.1−3+5+7+...+4989
=1514−149.1−3+49.49−3:2+1289
=15.45196.1−62489
=9196.−62389
=−928