You can show that (2 + (the square root of 5))^2 = 9 + 4 * (the square root of 5). So my final question is this: What is the square root of (9 + 4 * (the square root of 5)) ?
2 + (the square root of 5)
9 + 2 * (the square root of 5)
3 + 2 * (the square root of 5)
3 + (the square root of 5)