Cyyddtwtytryubgffyyttu
Giới thiệu về bản thân
Xét vế phải 1 − 1 2 + 1 3 − 1 4 + . . . . . + 1 199 − 1 200 1− 2 1 + 3 1 − 4 1 +.....+ 199 1 − 200 1 = ( 1 + 1 3 + 1 5 + . . + 1 199 ) − ( 1 2 + 1 4 + . . . + 1 200 ) (1+ 3 1 + 5 1 +..+ 199 1 )−( 2 1 + 4 1 +...+ 200 1 ) = ( 1 + 1 2 + 1 3 + 1 4 + 1 5 + . . . + 1 199 + 1 200 ) − 2. ( 1 2 − 1 4 − . . . − 1 200 ) (1+ 2 1 + 3 1 + 4 1 + 5 1 +...+ 199 1 + 200 1 )−2.( 2 1 − 4 1 −...− 200 1 ) = 1 + 1 2 + 1 3 + 1 4 + 1 5 + . . . + 1 199 + 1 200 − 1 − 1 2 − . . . − 1 100 1+ 2 1 + 3 1 + 4 1 + 5 1 +...+ 199 1 + 200 1 −1− 2 1 −...− 100 1 = 1 101 + 1 102 + . . . + 1 200 101 1 + 102 1 +...+ 200 1
Câu này =1352
=-202 100. Chắc chắn được 10 điểm luôn
S vì =5o5. Hihi
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