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avatar+111 

if a is real and the product of (a+6i)(5-31) is a real number, then find a

 
 Jun 23, 2022
 #1
avatar+123309 
+2

I think you might mean  this  ???

 

(a + 6i) ( 5 - 3i)

 

5a + 30i - 3ai  - 18i^2

 

5a + 30i - 3ai + 18

 

a =  10

 

Because

 

5 (10)  + 30i  -3(10)i + 18  =

 

50 + 30i - 30i + 18  =

 

68

 

 

cool cool cool

 
 Jun 23, 2022
 #2
avatar+111 
+2

Yeah, it's 5-3i.

 
Blizzardshine  Jun 23, 2022

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