Answer:
(4 + 7i)(4 - 7i)
Step-by-step explanation:
Factors of the form of a conjugate pair always produce a real number
(a + bi)(a - bi) ← produce a real number product ( a and b are real ), that is
(a + bi)(a - bi) ← expand using FOIL
= a² - bi² ( i² = - 1)
= a² + b² ← a real number
Thus
(4 + 7i)(4 - 7i)
= 16 - 49i²
= 16 + 49 = 65
Answer:
the correct answer is the last one, (4+7i)(4-7i)
Step-by-step explanation:
