b: =1-1/2+1/2-1/3+...+1/9-1/10=9/10
a: =1+1/4=5/4
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Các câu hỏi tương tự
Tinh hon so sau :
1 1/2 +2 1/6 + 3 1/12 + 4 1/20 + 5 1/30 + 6 1/42 + 7 1/56 + 8 1/72 +9 1/90 +1/10
1/90-1/72-1/56-1/42-1/30-1/20-1/12-1/6-1/2
1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90
a) 1/2+1/3+1/4+1/5+...+1/9+1/10
b) 1/12+1/20+1/30+1/42+1/56+1/72+1/90
Tính nhanh 1/2 + 1/6 + 1/12+ 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 + 1/110 = .....
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10
Tính bằng cách hợp lý
A, 5,4 + 6,5 + 7,6 + 8,7 - 4,4 - 5,5 - 6,6 - 7,7
B, 1/2+ 1/6 + 1/12 + 1/20+1/30+1/42+1/56+1/72+1/90
a) N = 1/2 + 1/6+ 1/12 + 1/20 + 1/30 +1/42 + 1/56 + 1/72 +1/90
b) 5/8 + 2/9 -2/5 + 3/8 + 4/9 + 1/3 - 3/5 =
c) 4 1/5 + 5 1/3 - 2 2/3 x 3 1/5 + 9/25 : 9/20 =
tính nhanh
1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
cac ban giup mik voi