Question

So sánh : (-5)³⁹ và (-2)⁹¹

Answer 1

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

Answer 2

Ta có: 5^35 = (5^3)^(35/3) = 125^(35/3) ; 2^91 = (2^7)^13 = 128^13
mà 128^13 > 125^(35/3) [128 > 125 và 13 > 35/3] 

Answer 3

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Answer 4

Ta có:

5³⁹ = (5³)¹³ = 125¹³

2⁹¹ = (2⁷)¹³ = 128¹³

Vì 125¹³ < 128¹³

=> 5³⁹ < 2⁹¹

=> (-5)³⁹ > (-2)⁹¹