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1. 1 ly có 0,75l
2. 1 chiếc áo mất 1,2 m vải
3. mỗi người nhận 1/2 cái bánh
4. mỗi chai có 0,5 l sữa
5.
a) \(=\frac{2}{3}\)
b)\(\frac{17}{19}\)
c)\(\frac{1}{2}\)
\(\frac{1}{1\times3}\) \(+\) \(\frac{1}{3\times5}\) \(+\) \(\frac{1}{5\times7}\) \(+\) \(...\) \(\frac{1}{19\times21}\)
\(=\) \(\frac{943}{1995}\)
A=1-1 phần 2 +1 phần 2 -1 phần 3.... + 1phan19 - 1 phần 21
A= 1- 1 phần 21
A= 20 phần 21
\(a,\frac{3\times4\times7}{12\times8\times9}\)
\(=\frac{3\times4\times7}{3\times4\times8\times9}\)
\(=\frac{7}{72}\)
\(b,\frac{4\times5\times6}{12\times10\times8}\)
\(=\frac{4\times5\times3\times2}{4\times3\times5\times2\times8}\)
\(=\frac{1}{8}\)
\(c,\frac{5\times6\times7\times9}{12\times7\times27}\)
\(=\frac{5\times6\times7\times9}{6\times2\times7\times9\times3}\)
\(=\frac{5}{6}\)
\(d,\frac{5\times6\times7}{12\times14\times15}\)
\(=\frac{5\times6\times7}{6\times2\times7\times2\times5\times3}\)
\(=\frac{1}{12}\)
a) \(\frac{3\times4\times7}{12\times8\times9}=\frac{3\times4\times7}{3\times4\times8\times9}=\frac{7}{8\times9}=\frac{7}{72}\)
b) \(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{6\times2\times2\times5\times4\times2}=\frac{1}{2\times2\times2}=\frac{1}{8}\)
c) \(\frac{5\times6\times7\times9}{12\times7\times27}=\frac{5\times6\times9}{12\times27}=\frac{5\times6\times9}{2\times6\times3\times9}=\frac{5}{2\times3}=\frac{5}{6}\)
d) \(\frac{5\times6\times7}{12\times14\times15}=\frac{5\times6\times7}{2\times6\times2\times7\times3\times5}=\frac{1}{2\times2\times3}=\frac{1}{12}\)
a) \(\frac{2\cdot3\cdot5}{70}=\frac{30}{70}=\frac{3}{7}\)
b) \(\frac{2\cdot6\cdot11}{33\cdot24}=\frac{2\cdot6\cdot11}{3\cdot11\cdot2\cdot2\cdot6}=\frac{1}{6}\)
c) \(\frac{21\cdot45}{9\cdot7\cdot5\cdot3}=\frac{3\cdot7\cdot5\cdot9}{9\cdot7\cdot5\cdot3}=1\)
Chúc bạn học tốt.
=\(2\)x(\(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{19}-\frac{1}{21}\))
=2x(\(\frac{1}{3}-\frac{1}{21}\))
=2x\(\frac{2}{7}\)
=\(\frac{4}{7}\)
\(A=\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{19.21}\)
\(2A=\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{19.21}\)
\(2A=\frac{2}{3}-\frac{2}{5}+\frac{2}{5}-\frac{2}{7}+...+\frac{2}{19}-\frac{2}{21}\)
\(2A=\frac{2}{3}-\frac{2}{21}\)
\(2A=\frac{4}{7}\)
\(A=\frac{2}{7}\)
Ta có :
A = \(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{13}-\frac{1}{15}\)
A = \(\frac{1}{1}-\frac{1}{15}\)
A = \(\frac{14}{15}\)
Ủng hộ mik nhá ^_^"
\(A=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{13}-\frac{1}{15}\)
\(A=1-\frac{1}{15}\)
\(A=\frac{14}{15}\)
Chúc bạn zui~^^
1=3/3=4/4=5/5=...
=> 1+1/1*3=3/1*3=1/1
=> 1+1/2*4=4/2*4=1/2
=>...
Bieu thuc se con lai la 1*1/2*1/3*1/4*1/5
Vay A=1/120
\(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}\)
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\)
\(=1-\frac{1}{11}=\frac{10}{11}\)
SAI HẾT RỒI.........CẦN THÌ TỚ GIẢI LẠI CHO !!
thế này :
= \(\frac{1}{2}\left(\frac{2}{3.5}+\frac{2}{5.7}+......+\frac{2}{11.13}\right)\)
= \(\frac{1}{2}\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{11}-\frac{1}{13}\right)\)
= \(\frac{1}{2}\left(\frac{1}{3}-\frac{1}{13}\right)\)
= \(\frac{1}{2}.\frac{10}{39}\)
= \(\frac{5}{39}\)
Vậy kq = \(\frac{5}{39}\)