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\(N=\dfrac{\dfrac{2.2}{3}\left(\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{11}\right)}{\dfrac{6.6}{2}\left(\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{11}\right)}=\dfrac{4}{\dfrac{3}{\dfrac{36}{2}}}=24\)
a: \(=\dfrac{1}{4}-\dfrac{3}{2}-\dfrac{1}{4}+\dfrac{1}{4}\cdot12=-\dfrac{3}{2}+3=\dfrac{3}{2}\)
c: \(=8\cdot\dfrac{1}{24}+\dfrac{-2}{5}\cdot\dfrac{15}{2}=3-3=0\)
e: 303/304=1-1/304
516/517=1-1/517
mà 1/304>1/517
nên 303/304<516/517
h: 713/715=1-2/715
203/205=1-2/205
mà 2/715<2/205
nên 713/715>203/205
Câu 3:
a. \(\dfrac{5}{12}+\dfrac{7}{12}\)=\(\dfrac{12}{12}=1\)
b. \(\dfrac{9}{4}-\dfrac{-7}{5}=\dfrac{45}{20}-\dfrac{-28}{20}=\dfrac{73}{20}\)
c.\(\dfrac{-5}{7}+\dfrac{3}{4}+\dfrac{-1}{5}+\dfrac{-2}{5}+\dfrac{1}{4}\)
=\(\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\dfrac{-1}{5}\)
=\(\dfrac{-7}{7}+\dfrac{4}{4}+\dfrac{-1}{5}\)
= -1+ 1 +\(\dfrac{-1}{5}\)
= 0 + \(\dfrac{-1}{5}\)=\(\dfrac{-1}{5}\)
a) 5/12+ 7/12
= 12/12
=1
b) 9/4- (-7/5)
= 9/4+ 7/5
=45/ 20+ 28/ 20
= 73/ 20
1:
a: 32-(-1,6)=32+1,6=33,6
b: (-0,5)*1,23=123/100*(-1/2)=-123/200
c: =-2,3-7,7=-10
d: =13/40-321/100
=65/200-642/200=-577/200
2:
a: =-42/5*16/5=-672/25=-26,88
b: =3,176-3,284=-0,108
c: =-2,89+8,075+3,14
=0,25+8,075=8,325
\(=\dfrac{1}{2}\left(\dfrac{2}{3\cdot5}+\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+\dfrac{2}{9\cdot11}+\dfrac{2}{11\cdot13}\right)\)
\(=\dfrac{1}{2}\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{13}\right)\)
\(=\dfrac{1}{2}\cdot\dfrac{10}{39}=\dfrac{5}{39}\)