Given that a and b are the solutions of the quadratic equation x² - 9x + 20 = 0, what is the value of a² + b² + ab?

Explanation

We need to find the value of a² + b² + ab. Notice that a² + b² + ab can be rewritten as (a + b)² - ab. From the equation x² - 9x + 20 = 0, the sum of roots a + b = 9 and the product ab = 20. Substituting these values, we get (9)² - 20 = 81 - 20 = 61. Therefore, the correct answer is 61.