Answer:
22
Step-by-step explanation:
Given
([tex]\sqrt{5}[/tex] + [tex]\sqrt{17}[/tex] i )([tex]\sqrt{5}[/tex] - [tex]\sqrt{17}[/tex] i ) ← expand factors using FOIL
= ([tex]\sqrt{5}[/tex] )² - ([tex]\sqrt{17}[/tex] )² i² ← i² = - 1
= 5 - 17(- 1)
= 5 + 17
= 22