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\(\frac{1}{6}\) + \(\frac{2}{15}\) + \(\frac{3}{40}\) + \(\frac{4}{96}\) + \(\frac{5}{204}\)
= \(\frac{3}{10}\)+\(\frac{3}{40}\)+ \(\frac{4}{96}\) + \(\frac{5}{204}\)
=\(\frac{3}{8}\)+\(\frac{4}{96}\)+ \(\frac{5}{204}\)
= \(\frac{5}{12}\)+ \(\frac{5}{204}\)
Hok tốt !
k nha <3
= \(\frac{15}{34}\)
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\(A=\frac{3-2}{2\times3}+\frac{5-3}{3\times5}+\frac{8-5}{5\times8}+...\frac{38-30}{30\times38}+\frac{47-38}{38\times47}\)
\(A=\frac{3}{2\times3}-\frac{2}{2\times3}+\frac{5}{3\times5}-\frac{3}{3\times5}+...\frac{38}{30\times38}-\frac{30}{30\times38}+\frac{47}{38\times47}-\frac{38}{38\times47}\)
\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}+...+\frac{1}{30}-\frac{1}{38}+\frac{1}{38}-\frac{1}{47}\)
\(A=\frac{1}{2}-\frac{1}{47}=\frac{47}{94}-\frac{2}{94}=\frac{45}{94}\)
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100 - 98 + 96 - 94 + ... + 8 - 6 + 4 - 2
= 2 + 2 + ... + 2 + 2 ( 50 số 2 )
= 2 . 50
= 100
100-98+96-94+...+8-6+4-2
=(100-98)+(96-94)+...+(8-6)+(4-2) ( có (100-2)/2+1=50 số và 50/2=25( nhóm)
=2+2+...+2 ( có 25 số 2)
=2*25
=50
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\(\dfrac{2}{3}+\dfrac{2}{6}+\dfrac{2}{12}+\dfrac{2}{24}+\dfrac{2}{48}+\dfrac{2}{96}+\dfrac{2}{192}\)
\(=2\times\left(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{24}+\dfrac{1}{48}+\dfrac{1}{96}+\dfrac{1}{192}\right)\)
\(=2\times\left(\dfrac{64+32+16+8+4+2+1}{192}\right)\)
\(=\dfrac{127}{96}\)
2/3+2/6+2/12+2/24+2/48+2/96+2/192
=2/3+1/3+1/6+1/12+1/24+1/48+1/96
=\(\dfrac{64+32+16+8+4+2+1}{96}\)
=\(\dfrac{127}{96}\)
1/6+2/15+3/40+4/96+5/204=15/34
Bạn giải hết ra , làm vậy ai chả làm được !