Let's plug in the values of a and b into the expression: 2(-6)² + 5(2)². First, calculate the squares: (-6)² = 36 and (2)² = 4. Now substitute these values back into the expression: 2(36) + 5(4). Finally, calculate: 2(36) + 5(4) = 72 + 20 = 92. So, the value of 2a² + 5b² when a = -6 and b = 2 is 92.