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What number must we add to 3-5i  to get 2+7i ? Here, i^2=-1

 Dec 28, 2020
 #1
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We can turn this problem into a subtraction problem:  (2+7i) - (3-5i). 

Since the order of subtraction/addition problems don't matter (a+b=b+a and a-b=-b+a), we can turn the problem into: (2-3) + (7i - -5i)

Subtracting a negative number is like adding the positive version of it: (2-3) + (7i+5i)

Doing the parts individually, 2-3 = -1 and 7i+5i = 12i.

Finally, we can combine them and our solution is -1 + 12i or 12i - 1. 

I hope this helped :)

 Dec 28, 2020
edited by Guest  Dec 28, 2020
 #3
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Nicely done guest.  :)

 

By convention, the real part must go first.     -1+12i

Melody  Dec 28, 2020
 #4
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Thank you, I learned something new today. 

Guest Dec 28, 2020
 #5
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That is excellent!

Melody  Dec 28, 2020
 #6
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thank you!

xxJenny1213xx  Dec 28, 2020
 #2
avatar+112000 
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What number must we add to 3-5i  to get 2+7i ? Here, i^2=-1

 

3+ -1=2

-5+ 12 = 7

 

so the answer is     -1+12i

 

 

For addition and subtraction you can treat the i like it is just an ordinary pronumeral.

 Dec 28, 2020
 #7
avatar+360 
+1

thank you!

xxJenny1213xx  Dec 28, 2020

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