a, >

b, <

c, <

cái nào mũ lớn hơn thì nó lớn lơn

a)Ta có : \(3^{39}=\left(3^{13}\right)^3=1594323^3\)
  \(11^{21}=\left(11^7\right)^3=19487171^3\)
Vì \(1594323< 19487171\)
\(=>1594323^3< 19487171^3\)
\(=>3^{39}< 11^{21}\)
Vậy \(3^{39}< 11^{21}\)
   b)Ta có : \(199^{20}=\left(199^4\right)^5=1568239201^5\)
                \(2002^{15}=\left(2002^3\right)^5=8024024008^5\)
Vì \(1568239201< 8024024008\)
\(=>1568239201^5< 8024024008^5\)
\(=>199^{20}< 2002^{15}\)
Vậy \(199^{20}< 2002^{15}\)
c) Ta có:\(125^{90}=\left(125^3\right)^{30}=1953125^{30}\)
            \(25^{120}=\left(25^4\right)^{30}=390625^{30}\)
Vì \(1953125>390625\)
\(=>1953125^{30}>390625^{30}\)
\(=>125^{90}>25^{120}\)
Vậy \(125^{90}>25^{120}\)
d)Ta có : \(3^{500}=\left(3^5\right)^{100}=243^{100}\)
              \(7^{300}=\left(7^3\right)^{100}=343^{100}\)
Vì \(243< 343\)
\(=>243^{100}< 343^{100}\)
\(=>3^{500}< 7^{300}\)
Vậy \(3^{500}< 7^{300}\)
Phù , cuối cùng cũng viết xong . Mỏi tay quá ! À , chúc bạn học tốt nhé !

\(\)

-25/20 < 20/25

15/21 > 21/49

-19/49 > -23/47

a, \(\dfrac{18}{24}\) = \(\dfrac{3}{4}\)                            \(\dfrac{15}{25}\) = \(\dfrac{3}{5}\) 

     \(\dfrac{3}{4}\)  >  \(\dfrac{3}{5}\) vậy \(\dfrac{18}{24}\) > \(\dfrac{15}{25}\)

b, \(\dfrac{21}{15}\) = \(\dfrac{7}{5}\)                            \(\dfrac{28}{24}\) = \(\dfrac{7}{6}\)

      \(\dfrac{7}{5}\)  >  \(\dfrac{7}{6}\) vậy \(\dfrac{21}{15}\)  >  \(\dfrac{28}{24}\) 

ᵃ, ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{18}{24}=\dfrac{3}{4}\) ;

 ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{15}{25}=\dfrac{3}{5}\)

Vì \(\dfrac{3}{4}>\dfrac{3}{5}\\ \Rightarrow\dfrac{18}{24}>\dfrac{15}{25}\)

ᵇ, ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{21}{15}=\dfrac{7}{5}\\ \dfrac{28}{24}=\dfrac{7}{6}\)

Vì \(\dfrac{7}{5}>\dfrac{7}{6}\\ \Rightarrow\dfrac{21}{15}>\dfrac{28}{24}\)

21/35=3/5; 12/20=3/5

=>21/35=12/20

24/35<1<21/7

35/49=5/7; 40/64=5/8

=>35/49>40/64

2424/4848=1/2

9/11=1-2/11

13/15=1-2/15

mà 2/11>2/15

nên 9/11<13/15

19/15>11/15

khó

a>\(16^{19}=2^{4^{19}}=2^{76}\\ 8^{25}=2^{3^{25}}=2^{75}\)

16^19>8^25