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Bài 1:
\(\dfrac{-13}{38}\) và \(\dfrac{29}{-88}\)
\(\dfrac{-13}{38}=\dfrac{-13.29}{38.29}=\dfrac{-377}{1102}\)
\(\dfrac{29}{-88}=\dfrac{-29}{88}=\dfrac{-29.13}{88.13}=\dfrac{-377}{1144}\)
Vì \(\dfrac{-377}{1102}< \dfrac{-377}{1144}\) nên \(\dfrac{-13}{38}< \dfrac{29}{-88}\)
\(\dfrac{-18}{31}\) và \(\dfrac{-1818}{3131}\)
\(\dfrac{-18}{31}\)
\(\dfrac{-1818}{3131}=\dfrac{-1818:101}{3131:101}=\dfrac{-18}{31}\)
Vì \(\dfrac{-18}{31}=\dfrac{-18}{31}\) nên \(\dfrac{-18}{31}=\dfrac{-1818}{3131}\)
Bài 2:
a) \(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-4}{156}+\dfrac{-3}{156}=\dfrac{-4+-3}{156}=\dfrac{-7}{156}\)
b) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-2}{3}+\dfrac{-3}{4}=\dfrac{-8}{12}+\dfrac{-9}{12}=\dfrac{-17}{12}\)
\(\frac{20}{29}=\frac{40}{58}>\frac{29}{58}=\frac{1}{2}=\frac{20}{40}>\frac{19}{40}\)
\(\frac{19}{18}>1>\frac{20}{31}\)
a) 7^13 = 7.7^12 = 7.(7^2)^6 = 7. 49^6 > 39^6
b) 9^36 = 9^4.9^32 = 9^4. (9^2)^16 = 9^4.81^16 > 79^16
\(4+\sqrt{33}=\sqrt{16}+\sqrt{33}\)
Có: \(\sqrt{16}>\sqrt{14}\)
\(\sqrt{33}>\sqrt{29}\)
=> \(\sqrt{16}+\sqrt{33}>\sqrt{29}+\sqrt{14}\)
=> \(4+\sqrt{33}>\sqrt{29}+\sqrt{14}\)
Ta thấy :
\(\frac{20}{39}>\frac{14}{39}\)
\(\frac{22}{27}>\frac{22}{29}\)
\(\frac{18}{43}< \frac{18}{41}\)
\(\Rightarrow\frac{20}{39}+\frac{22}{27}+\frac{18}{43}>\frac{14}{39}+\frac{22}{29}+\frac{18}{41}\)
=> A > B
Bài 1: \(\left(\frac{-1}{16}\right)^{100}=\frac{1}{\left(2^4\right)^{100}}=\frac{1}{2^{400}}>\frac{1}{2^{500}}=\left(\frac{-1}{2}\right)^{500}.\)
Bài 2: \(100^{99}+1>100^{68}+1\Rightarrow\frac{1}{100^{99}+1}< \frac{1}{100^{68}+1}\Rightarrow\frac{-99}{100^{99}+1}>\frac{-99}{100^{68}+1}\)
\(\Rightarrow100+\frac{-99}{100^{99}+1}>100+\frac{-99}{100^{68}+1}\Rightarrow\frac{100^{100}+1}{100^{99}+1}>\frac{100^{69}+1}{100^{68}+1}\)
b: -1989/1991>-1>-2001/2000
c: 1/1000>0>-120/157
i: 2021/2020=1+1/2020
2022/2021=1+1/2021
mà 1/2020>1/2021
nên 2021/2020>2022/2021
f: 91/87>1>102/104
a) Ta có: \(4+\sqrt{33}=\sqrt{16}+\sqrt{33}\)
Vì \(\sqrt{16}>\sqrt{14};\sqrt{33}>\sqrt{29}\)
\(\Rightarrow4+\sqrt{33}>\sqrt{29}+\sqrt{14}\)
b) Ta có: \(\sqrt{23}+\sqrt{15}< \sqrt{25}+\sqrt{16}=5+4=9=\sqrt{81}\)