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a, \(\frac{15}{7}=2\frac{1}{7}\); \(\frac{-18}{4}=-4\frac{2}{4}\) ; \(\frac{-21}{8}=-2\frac{5}{8}\)
b, \(1\frac{1}{4}=\frac{5}{4};-3\frac{2}{5}=\frac{-17}{5};-7\frac{1}{2}=-\frac{15}{2}\)
a) Chuyển các phân số sau về dạng hỗn số:
\(\frac{15}{7}\)=2\(\frac{1}{7}\)
\(\frac{-18}{4}\)=- 4\(\frac{2}{4}\)
-\(\frac{21}{8}\)=- 2\(\frac{5}{8}\)
b) Chuyển các hỗn số sau về dạng phân số:
1\(\frac{1}{4}\)=\(\frac{5}{4}\)
-3\(\frac{2}{5}\)=-\(\frac{17}{5}\)
-7\(\frac{1}{2}\)=-\(\frac{15}{2}\)
A = ( 2 + 2\(^2\)) + ( 2\(^2\)+ 2\(^3\)) + ...+ ( 2\(^{49}\)+ 2\(^{50}\))
A = 2 (1+2) + 2\(^2\)(1+2) + .....+ 2\(^{49}\)(1+2)
A = ( 1+2 )(2+2\(^2\)+.....+2\(^{49}\))
A = 3(2+2\(^2\)+.....+2\(^{49}\)) \(⋮\)3
a) 17.13+17.42-17.35
=17.(13+42-35)
=17.20=340
b) [25.(18-42)-10]:4+6
=(25.2-10):4+6
=40:4+6=16
c) 36:32+23.22-32.3
=34+25-33
=81+32-27=86
d) B=3.42-22.3
=3.(16-4)
=3.12=36
e)20220+3.[52.10-(23-13)2]
=1+3.(250-100)
=1+450=451
g) 27.77+24.27-27
=27.(77+24-1)
=27.100=2700
h) 5.23+79:77-12020
=40+72-1
=89-1=88
i) 120:{54[50:2+(32-2.4)]}
=120:[54(25+1)]
=120:1404=10/117
\(\dfrac{\dfrac{2}{5}+\dfrac{2}{7}-\dfrac{2}{9}-\dfrac{2}{11}}{\dfrac{4}{5}+\dfrac{4}{7}-\dfrac{4}{9}-\dfrac{4}{11}}=\dfrac{2.\left[\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right]}{4.\left[\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right]}\)\(=\dfrac{2}{4}=\dfrac{1}{2}\)
\(B=\dfrac{\dfrac{2}{5}+\dfrac{2}{7}-\dfrac{2}{9}-\dfrac{2}{11}}{\dfrac{4}{5}+\dfrac{4}{7}-\dfrac{4}{9}-\dfrac{4}{11}}=\dfrac{2.\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}{4.\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}=\dfrac{1}{2}\)
a: =(-2)+(-2)+...+(-2)=-2x10=-20
b: =(-3)+(-3)+...+(-3)+103=-3x50+103=-150+103=-47
=27 - 72022
=27 - 72022