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\(a,\frac{26}{60}+\frac{3}{15}=\frac{13}{30}+\frac{1}{5}=\frac{13}{30}+\frac{6}{30}=\frac{19}{30}\)
\(b,\frac{4}{26}+\frac{33}{78}=\frac{2}{13}+\frac{11}{26}=\frac{4}{26}+\frac{11}{26}=\frac{15}{26}\)
\(c,\frac{25}{40}-\frac{3}{12}=\frac{5}{8}-\frac{1}{4}=\frac{5}{8}-\frac{2}{8}=\frac{3}{8}\)
\(d,\frac{21}{27}+\frac{10}{54}+\frac{5}{15}=\frac{7}{9}+\frac{5}{27}+\frac{1}{3}=\frac{21}{27}+\frac{5}{27}+\frac{9}{27}=\frac{35}{27}\)
~Study well~
#Thạc_Trân
a) ta có: \(A=\frac{2017.2018-1}{2017.2018}=\frac{2017.2018}{2017.2018}-\frac{1}{2017.2018}=1-\frac{1}{2017.2018}\)
\(B=\frac{2018.2019-1}{2018.2019}=1-\frac{1}{2018.2019}\)
\(\Rightarrow\frac{1}{2017.2018}>\frac{1}{2018.2019}\)
\(\Rightarrow1-\frac{1}{2017.2018}< 1-\frac{1}{2018.2019}\)
=> A < B
a)A= 2017*2018/2017*2018-1/2017*2018=1-1/2017*2018
B = 2018*2019/2018*2019-1/2018*2019=1-1/2018*2019
vì 1/2017*2018>1/2018*2019=> A<B
b)
\(P=\left(1+\frac{1}{49}\right)+\left(1+\frac{2}{48}\right)+\left(1+\frac{3}{47}\right)+...+\left(1+\frac{48}{2}\right)+1=\frac{50}{49}+\frac{50}{48}+\frac{50}{47}+...+\frac{50}{2}+\frac{50}{50}\)
\(P=50.\left(\frac{1}{49}+\frac{1}{48}+\frac{1}{47}+...+\frac{1}{2}+\frac{1}{50}\right)=50.S\)
=> S/P = 1/50
a) 5/30+15/90+25/150+35/210+45/270
=1/6+1/6+1/6+1/6+1/6
=1/6 x 5
=5/6
b) 1/2+1/6+1/12+1/20+....+1/56
=1/1x2+1/2x3+1/3x4+1/4x5+.....1/7x8
=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+.......-1/7+1/7-1/8
=1/1-1/8
=7/8
c) mình chịu
a) 20/45 = 4/9 ; 15/35 = 3/7 ; 32/44 = 8/11
b) 15/108 = 5/36 ; 70/180 = 7/18 ; 20/255 = 4/51
c) 75/90 = 15/18 ; 77/99=7/9 ; 15/60 = 3/12