Let's solve the quadratic equation:

\[ 9x^2 - 30x + 225 = 0. \]

We can start by simplifying the equation. Notice the equation is in the standard form \( ax^2 + bx + c = 0 \), where \( a = 9 \), \( b = -30 \), and \( c = 225 \).

First, let's check if the quadratic can be further simplified or solved by factoring:

1. **Find two numbers that multiply to \( ac = 9 \times 225 = 2025 \) and add to \( b = -30 \).**

However, this can be factored directly because it is a perfect square trinomial:

\[ (3x - 15)^2 = 0. \]

2. **Solve for \( x \):**

From \((3x - 15)^2 = 0\), we take the square root of both sides:

\[ 3x - 15 = 0. \]

3. **Solve for \( x \):**

Add 15 to both sides:

\[ 3x = 15. \]

Divide by 3:

\[ x = 5. \]

Thus, the solution to the equation is \( x = 5 \).