Question

If the equation, x² + bx + 45 = 0 (b ∈ R) has conjugate complex roots and they satisfy z +1 = 2√10, then 

(1) b² – b = 42 

(2) b² + b = 12 

(3) b² + b = 72 

(4) b² – b = 30

Answer 1

Answer is (4) b² – b = 30

Assuming z is a root of the given equation,

Answer 2

Answer is (4) b² - b = 30