Solution
= Solution
The cubic is strictly increasing and has one real root. A rational root of the monic integer <polynomial> would be an integer divisor of $3$; testing $\pm1,\pm3$ gives none, so the root is irrational.
= Solution
The cubic is strictly increasing and has one real root. A rational root of the monic integer <polynomial> would be an integer divisor of $3$; testing $\pm1,\pm3$ gives none, so the root is irrational.