Tính tổng : A=38/25 + 9/10 - 11/15 + 13/21 - 15/28 + 17/36 - ................+197/4851-199/4950
HS
Những câu hỏi liên quan
Tính tổng \(A=\frac{38}{25}+\frac{9}{10}-\frac{11}{15}+\frac{13}{21}-\frac{15}{28}+\frac{17}{36}-...+\frac{197}{4851}-\frac{199}{4950}\)
(x-2)^2=38/25+9/10-11/15+13/21-15/28+17/36-...+197/4851-199/4950
Tính tổng : A=38/25 + 9/10 - 11/15 + 13/21 - 15/28 + 17/36 - ................+197/4851-199/4950
Tính tổng:
\(S=\frac{38}{25}+\frac{9}{10}-\frac{11}{15}+\frac{13}{21}-\frac{15}{28}+\frac{17}{36}-...+\frac{197}{4851}-\frac{199}{4950}\)
38/25+9/10-11/15+13/21-15/28+17/36_............+197/4851-199/4950
38/25+9/10-11/15+13/21-15/28+17/36_............+197/4851-199/4950
Tìm x, biết :
(x - 2)^2 = 38/25 + 9/10 - 11/15 + 13/21 - 15/28 + 17/36 - ..... + 197/4851 - 199/4950
Tìm x:
[x-2]2=38/25+9/10-11/15+13/21-15/28+17/36-...+197/4851-199/4950
H24
10 tháng 2 2015 lúc 13:59
Tính tổng : A=38/25 + 9/10 - 11/15 + 13/21 - 15/28 + 17/36 - ................+197/4851-199/4950
A= 38/25+9/10-11/15+13/21-15/28+17/36-...+197/4851-199/4950
Ta có thể viết lại : (9/20-11/15)+(13/21-15/28)+17/36-19/45...+(197/4851-199/4950)
Ta thấy:(9/10-11/15)=1/6=1/2x3=1/2-1/3
(13/21-15/28)=1/12=1/3x4=1/3-1/4
(17/36-19/45)=1/20=1/4x5=1/4-1/5
............................
Ta được:9/10-11/15+13/21-15/28+17/36-19/45...+197/4851-199/4950=1/2-1/3+1/3-1/4+1/4-1/5=24/50
Vậy:A= 38/25+24/50
A=2
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