So sánh
a) 3450 và 5300
b) 231 và 321
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\(a=\left[\left(-\dfrac{1}{2}\right)^5\right]^{107}=\left(-\dfrac{1}{32}\right)^{107}\)
\(b=\left[\left(-\dfrac{1}{3}\right)^3\right]^{107}=\left(-\dfrac{1}{27}\right)^{107}\)
mà -1/32>-1/27
nên a>b
\(3^{21}=3^{20}.3=9^{10}.3\)
\(2^{31}=2^{30}.2=8^{10}.2\)
Do \(9^{10}>8^{10},3>2\)
\(\Rightarrow9^{10}.3>8^{10}.2\Rightarrow3^{21}>2^{31}\)
\(3^{21}=3^{20}\cdot3\)
\(2^{31}=2^{30}\cdot2\)
mà \(3^{20}>2^{30}\)
nên \(3^{21}>2^{31}\)
1 ) \(a=231.239=\left(235-4\right)\left(235+4\right)=235^2-16< 235^2=b\)
2 ) \(a=61.80=61.40.2=122.40\)
\(b=43.120=43.40.3=129.40\)
Suy ra : b > a
a: \(\frac{60}{72}=\frac{60:12}{72:12}=\frac56\)
\(\frac{24}{36}=\frac{24:12}{36:12}=\frac23=\frac{2\times2}{3\times2}=\frac46\)
mà 5>4
nên \(\frac{60}{72}>\frac{24}{36}\)
b: \(\frac{-13}{18}=\frac{-13\times2}{18\times2}=\frac{-26}{36}\)
\(\frac{-7}{12}=\frac{-7\times3}{12\times3}=\frac{-21}{36}\)
mà -26<-21
nên \(-\frac{13}{18}<-\frac{7}{12}\)
c: \(\frac{4}{15}=\frac{4\times6}{15\times6}=\frac{24}{90}\)
\(\frac{7}{18}=\frac{7\times5}{18\times5}=\frac{35}{90}\)
mà 24<35
nên \(\frac{4}{15}<\frac{7}{18}\)
d: \(\frac{123}{321}>0;0>-\frac{312}{213}\)
Do đó: \(\frac{123}{321}>-\frac{312}{213}\)
a: \(\frac{60}{72}=\frac{60:12}{72:12}=\frac56\)
\(\frac{24}{36}=\frac{24:12}{36:12}=\frac23=\frac{2\times2}{3\times2}=\frac46\)
mà 5>4
nên \(\frac{60}{72}>\frac{24}{36}\)
b: \(\frac{-13}{18}=\frac{-13\times2}{18\times2}=\frac{-26}{36}\)
\(\frac{-7}{12}=\frac{-7\times3}{12\times3}=\frac{-21}{36}\)
mà -26<-21
nên \(-\frac{13}{18}<-\frac{7}{12}\)
c: \(\frac{4}{15}=\frac{4\times6}{15\times6}=\frac{24}{90}\)
\(\frac{7}{18}=\frac{7\times5}{18\times5}=\frac{35}{90}\)
mà 24<35
nên \(\frac{4}{15}<\frac{7}{18}\)
d: \(\frac{123}{321}>0;0>-\frac{312}{213}\)
Do đó: \(\frac{123}{321}>-\frac{312}{213}\)
a) Ta có: \(3^{450}=3^{3.150}=\left(3^3\right)^{150}=27^{150}\)
\(5^{300}=5^{2.150}=\left(5^2\right)^{150}=25^{150}\)
Vì 27>25 \(\Rightarrow3^{450}>5^{300}\)
b) \(2^{31}=2.2^{30}=2.\left(2^3\right)^{10}=2.8^{10}\)
\(3^{21}=3.3^{20}=3.\left(3^2\right)^{10}=3.9^{10}\)
Vì \(2.8^{10}< 3.9^{10}\Rightarrow2^{31}< 3^{21}\)
\(\)
a)\(3^{450}=\left(3^3\right)^{150}=27^{150};5^{300}=\left(5^2\right)^{150}=25^{150}\)
27150>25150 => 3450>5300
b)\(2^{31}=2.2^{30}=2.\left(2^3\right)^{10}=2.8^{10};3^{21}=3.3^{20}=3.\left(3^2\right)^{10}=3.9^{10}\)
2<3;810<910 => 2.810<3.910 => 231<321