To factor the trinomial \( x^2 - 11x + 28 \), we look for two numbers that multiply to \( 28 \) (the constant term) and add to \( -11 \) (the coefficient of \( x \)).
The numbers that satisfy these conditions are \( -7 \) and \( -4 \) because:
- \((-7) + (-4) = -11\)
- \((-7) \times (-4) = 28\)
Thus, we can factor the trinomial as:
\[ (x - 7)(x - 4) \]
So the answer is: \((x - 7)(x - 4)\)