If a and b are the roots of the equation x² - 9x + 20 = 0, find the value of a² + b² + ab?
Q1. If a and b are the roots of the equation x² - 9x + 20 = 0, find the value of a² + b² + ab?
Answer: 61
Explanation: For roots a and b: a+b = 9 and ab = 20; a²+b²+ab = (a+b)² − ab = 81 − 20 = 61.