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H = 10/56 + 10/140 + 10/260 +…..+ 10/1400
H = 5/28 + 5/70 + 5/130 +…..+ 5/700
H = 5 x (1/4.7 + 1/7.10 + 1/10.13 +…………+ 1/25.28)
H = 5/3 x (3/4.7 + 3/7.10 + 3/10.13 +………+ 3/25.28)
H = 5/3 x (1/4-1/7+1/7-1/10+1/10-1/13+……..+1/25-1/28)
H = 5/3 x (1/4-1/28)
H = 5/3 x 3/14 = 5/14
H = 10/56 + 10/140 + 10/260 + ... + 10/1400
H = 5/3 × (3/28 + 3/70 + 3/130 + ... + 3/700)
H = 5/3 × (3/4×7 + 3/7×10 + 3/10×13 + ... + 3/25×28)
H = 5/3 × (1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + ... + 1/25 - 1/28)
H = 5/3 × (1/4 - 1/28)
H = 5/3 × 3/14
H = 5/14
\(H=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+....+\frac{10}{1400}\)
\(=\frac{5}{4.7}+\frac{5}{7.10}+\frac{5}{10.13}+....+\frac{5}{25.28}\)
\(=\frac{5}{3}.\left(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+....+\frac{3}{25.28}\right)\)
\(=\frac{5}{3}.\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+....+\frac{1}{25}-\frac{1}{28}\right)\)
\(=\frac{5}{3}.\left(\frac{1}{4}-\frac{1}{28}\right)\)
\(=\frac{5}{3}.\frac{3}{14}=\frac{5}{14}\)
Rút gọn biểu thức H = \(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\) ta được =?
H=10/56+10/140+10/260+...+10/1400
H=10/56+10/1400
H=13/70
vay H=13/70
ai di qua nho h cho minh nhe
B = 10/56 + 10/140 + 10/260 + ...+ 10/1400
B= 5/28 + 5/70 +.....+10/700
= 5/(4.7)+5/(7.10)+....5/(25.28)
3B= 5( 1/4 - 1/7 +1/7-1/10+......+1/25-1/28)
3B = 5 (1/4-1/28)
3B=15/14
B = 15/14 : 3
B = 5/14
S = 10/56 + 10/140 + 10/260 + ....... + 10/1400
S = 5/28 + 5/70 + 5/130 + 5/700
3S/5 = 3/4 x 7 + 3/7 x 10 + 30/10 x 13 + ....... + 3/25 x 28
3S/5 = 1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + ........ + 1/25 - 1/28
3S/5 = 1/4 - 1/28
3S/5 = 3/14
S = 3/14 x 5/3
S = 5/14
Vậy S = 5/14
\(S=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+\frac{10}{1400}\)
\(S=\frac{5}{28}+\frac{5}{70}+\frac{5}{130}+...+\frac{5}{700}\)
\(S=\frac{5}{4.7}+\frac{5}{7.10}+\frac{5}{10.13}+...+\frac{5}{25.28}\)
\(S=5.\left(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+...+\frac{3}{25.28}\right)\)
\(S=5.\left(\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+...+\frac{1}{25.28}\right)\)
\(S=5.\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{25}-\frac{1}{28}\right)\)
\(S=5.\left(\frac{1}{4}-\frac{1}{28}\right)\)
\(S=5.\frac{3}{14}=\frac{15}{14}\)
Vậy \(S=\frac{15}{14}\)
A = 10/56 + 10/140 + 10/260 + .......+ 10/1400
A = 5/28 + 5/70 + 5/130 +.........+ 5/700
3A/5 = 3/4.7 + 3/7.10 + 3/10.13 +.......+ 3/25.28
3A/5 = 1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 +........+ 1/25 - 1/28
3A/5 = 1/4 - 1/28
3A/5 = 3/14
A = 3/14 . 5/3
A = 5/14
Vậy A = 5/14
A= 5/3.(3/28+3/70+3/130+...+3/700) A=5/3.(3/4.7+3/7.10+3/10.13+...+3/25.28)
A=5/3.(1/4-1/7+1/7-1/10+1/10-1/13+...+1/25-1/28)
A=5/3(1/4-1/28)
A=5/3.(7/28-1/28)
A=5/3.3/14
A=5/14
Ta có:\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
=\(\frac{5}{3}\times\left(\frac{3}{28}+\frac{3}{70}+\frac{3}{130}+...+\frac{3}{700}\right)\)
=\(\frac{5}{3}\times\left(\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}+...+\frac{3}{25\times28}\right)\)
=\(\frac{5}{3}\times\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{25}-\frac{1}{28}\right)\)
=\(\frac{5}{3}\times\left(\frac{1}{4}-\frac{1}{28}\right)\)
=\(\frac{5}{3}\times\frac{3}{14}\)
=\(\frac{5}{14}\)
Ko bít có đúng ko nhưng cứ thử nhé