Which is bigger, $2^{5}$ or $5^{2}$ ?

Q: Which is bigger, 2^5 or 5^2?

2^5 is bigger: 2^5 = 32 and 5^2 = 25.

$2^{5}$ is bigger: $2^{5}$ = 32 and $5^{2}$ = 25.

2^{5} = 32\ >\ 5^{2} = 25

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The curve ln x / x, which decides every comparison of a^b with b^a. 2^5 against 5^2 is the same question as which of the two marked points is higher; the curve peaks at x = e.

How to work it out

1
Compute both exactly: $2^{5}$ = 32 and $5^{2}$ = 25.
2
So $2^{5}$ is bigger.
3
The reason: taking logs, $a^{b}$ against $b^{a}$ is the same as $\frac{\ln a}{a}$ against $\frac{\ln b}{b}$ . The function $\frac{\ln x}{x}$ rises until $x = e \approx 2.718$ and falls afterwards. For 2 and 5 it depends: $2^{4}$ = $4^{2}$ are equal, $2^{3}$ < $3^{2}$ , and $2^{b}$ > $b^{2}$ for every b ≥ 5.
$\frac{\ln 2}{2}\ >\ \frac{\ln 5}{5}$

LaTeX source of the formulas on this page

\[ 2^{5} = 32\ >\ 5^{2} = 25 \]
\[ \frac{\ln 2}{2}\ >\ \frac{\ln 5}{5} \]

Questions

Which is bigger,

2^{5}

5^{2}

$2^{5}$ is bigger: $2^{5}$ = 32 and $5^{2}$ = 25.

Which is bigger, 252^{5}25 or 525^{2}52?

How to work it out

Questions

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Which is bigger, $2^{5}$ or $5^{2}$ ?