a + b = 11 a = 11 -b
a * b = (11 - b ) * b = 11 b - b² = 20
b² - 11b + 20 = 0 Δ = (-11)² - 4* 1 * 20 = 41
x1 = (11 + √41)/2 ≈8,701562119 x2= (11 -√41)/2 ≈ 2,298437881
entonces a² + b² = ((11 + √41)/2)² + ((11 - √41)/2)² =
(81 + 11√41)/2 + (81 - 11√41)/2 = 81
a² + b² =81
