Ta có: 

\(2^{91}=\left(2^{13}\right)^7=8192^7\)

\(5^{35}=\left(5^5\right)^7=3125^7\)

Mà: \(3125^7< 8192^7\)

\(\Rightarrow2^{91}>5^{35}\)

k cho mình mình k lại nha    Tiểu Thư Họ Phạm

\(\left(-5\right)^{39}=\left[\left(-5\right)^3\right]^{13}=\left(-125\right)^{13}\)

\(\left(-2\right)^{91}=\left[\left(-2\right)^7\right]^{13}=\left(-128\right)^{13}\)

\(\Rightarrow\left(-128\right)^{13}< \left(-125\right)^{13}\)

\(\Rightarrow\left(-5\right)^{39}>\left(-2\right)^{91}\)

Ta có:

\(\left(-5\right)^{39}=\left[\left(-5\right)^3\right]^{13}=\left(-125\right)^{13}\)

\(\left(-2\right)^{91}=\left[\left(-2\right)^7\right]^{13}=\left(-128\right)^{13}\)

Ta thấy: 

\(-125>-128\)

\(\Rightarrow\left(-125\right)^{13}>\left(-128\right)^3\)

\(\Rightarrow\left(-5\right)^{39}>\left(-2\right)^{91}\)

Ta có:

\(\left(-5\right)^{39}=\left[-5^3\right]^{13}=-125^{13}\)

\(\left(-2\right)^{91}=\left[-2^7\right]^{13}=-128^{13}\)

Vì \(-125^{13}< -128^{13}\) nên \(\left(-5\right)^{39}< \left(-2\right)^{91}\)

( -5 ) ^ 39 > -2 ^ 91

Bài 1:

a: Sửa đề: 1/3^200

1/2^300=(1/8)^100

1/3^200=(1/9)^100

mà 1/8>1/9

nên 1/2^300>1/3^200

b: 1/5^199>1/5^200=1/25^100

1/3^300=1/27^100

mà 25^100<27^100

nên 1/5^199>1/3^300

Ta có: (-5)³⁹=(-5)^3.13=\(\left[\left(-5\right)^3\right]^{13}=\left(-125\right)^{13}\)

          (-2)⁹¹=(-2)^13.7=\(\left[\left(-2\right)^7\right]^{13}=\left(-8192\right)^{13}\)

Vì (-125)>(-8192) => (-5)³⁹>(-2)⁹¹

Ta có:12⁸=(12⁴)²=20736²

           8¹²=(8⁶)²=262144²

                 Vì 20736²<262144²

Vậy 12⁸< 8¹²

b)Ta có:(-5)³⁹=[(-5)³]¹³=(-125)¹³

              (-2)⁹¹=[(-2)⁷]¹³=(-128)¹³

                   Vì (-128)¹³<(-125)¹³

Vậy (-2)⁹¹<(-5)³⁹

Ta có: 12⁸=(12⁴)²=20736²

8¹²=(2⁶)²=64²

Vì 20736>64 nên 20736²>64²hay 12⁸>8¹²

mình sai rồi xin lỗi nha cho mình sửa lại

Ta có: 12⁸=(12⁴)²=20736²

8¹²=(8⁶)²=262144²

Vì 20736<262144 nên 20736²<262144²hay 12⁸<8¹²

(-5)^39>(-2)^91

Ta có: \(\left(-5\right)^{39}=\left[\left(-5\right)^3\right]^{13}=\left(-125\right)^{13}\)

\(\left(-2\right)^{91}=\left[\left(-2\right)^7\right]^{13}=\left(-128\right)^{13}\)

Vì \(-125>-128\Rightarrow\left(-125\right)^{13}>\left(-128\right)^{13}\)

\(\Rightarrow\left(-5\right)^{39}>\left(-2\right)^{91}\)

a) \(12^8=\left(12^2\right)^4=144^4\)

     \(8^{12}=\left(8^3\right)^4=512^4\)

Vì \(144^4< 512^4\Rightarrow12^8< 8^{12}\)

Vậy \(12^8< 8^{12}\)

b) \(\left(-5\right)^{39}=\left[\left(-5\right)^3\right]^{13}=\left(-125\right)^{13}\)

     \(\left(-2\right)^{91}=\left[\left(-2\right)^7\right]^{13}=\left(-128\right)^{13}\)

Vì \(\left(-125\right)^{13}>\left(-128\right)^{13}\Rightarrow\left(-5\right)^{39}>\left(-2\right)^{91}\)

Vậy \(\left(-5\right)^{39}>\left(-2\right)^{91}\)

bài này mik làm đc rùi,khỏi trả lời nhá 

a) Ta có: 12⁸ = (3.4)⁸ = 3⁸.4⁸ = 3⁸.(2²)⁸ = 3⁸.2¹⁶

8¹² = (2³)¹² = 2³⁶ = 2²⁰.2¹⁶ = (2²)¹⁰.2¹⁶ = 4¹⁰.2¹⁶

Vì 3⁸.2¹⁶ < 4¹⁰.2¹⁶

=> 12⁸ < 8¹²

b) (-5)³⁹ = -5³⁹ = -(5³)¹³ = -125¹³

(-2)⁹¹ = -2⁹¹ = -(2⁷)¹³ = -128¹³

Vì 125¹³ < 128¹³

=> -125¹³ > -128¹³

=> (-5)³⁹ > (-2)⁹¹