To prove that the sum \( 34 + \sqrt{10} \) is irrational, we start by recognizing that \( 34 \) is a rational number, as it can be expressed as \( \frac{34}{1} \). However, \( \sqrt{10} \) is an irrational number because it cannot be expressed as a fraction of two integers.
Now we will assume for the sake of contradiction that the sum \( 34 + \sqrt{10} \) is rational. If it were rational, let's denote it as \( r \):
\[
r = 34 + \sqrt{10}
\]
Rearranging this gives us:
\[
\sqrt{10} = r - 34
\]
Since \( r \) is rational and \( 34 \) is also rational, their difference \( (r - 34) \) would also be rational. This implies that \( \sqrt{10} \) would be rational, which contradicts the established fact that \( \sqrt{10} \) is indeed irrational.
Therefore, our assumption that \( 34 + \sqrt{10} \) is rational must be false, leading us to conclude that \( 34 + \sqrt{10} \) is irrational.
In summary, the sum \( 34 + \sqrt{10} \) is irrational because it is the sum of a rational number (34) and an irrational number (\(\sqrt{10}\)), and the sum of a rational and an irrational number is always irrational.