Give the answer in a + bi form?

Question

-3 over 4 - i

I got   -3 (4 - i ) over (4 - i) ( 4+i ) = -3 (4 - i ) over 4 ^2 - i ^ 2 = -3 ( 4 - i ) over 16 - ( - 1 ) = -3 ( 4 - i ) over 17 = -12 + 3 i over 17 =  -12 over 17 + 3 over 17 i 

when I got to the fraction part there was obviously no common denominator for 17 so i split it into two fractions...wrong.

Jay · Accepted Answer

-3 / (4-i)
multiply throughout by the conjugate of the denominator which is (4+i):
-3(4+i) / (16-i^2)
(-12-3i) / 17
(-12/17) + (-3/17)i

RobertMathmanJones · Answer

...-3
-------
4 - i

...-3....4 + i
------x-------
4 - i....4 + 1

-3(4 + i)
----------
16 - iÂ²

-12 - 3i
----------
16 - (-1)

-12 - 3i
---------
16 + 1

-12 - 3i
----------
....17

OR in a + bi  form

-12......3
----..-..--- i............ANSWER
17.....17


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A PRESENT FOR YOU
Ask someone to write a number, say a five-digit number.
(Can be a 2-digit.....3-digit.....4-digit....ect..…
Suppose the number written is 
57836
Now, without showing the asker, you write a number on
a sheet of paper and keep it folded. You have to write the
number by subtracting 2 from the above number and 
adding 2 in front which will be....
257834
Next, ask the person to write another five-digit number 
below his original number. Suppose he writes 37589. 
So you now have...
57836
37589
Now you write a five-digit number below it in such a 
way that each digit is 9 minus digit above. You now have...
57836
37589
62410
Ask the person to add one more 5-digit number. If he 
adds 54732, you add below it 45267. Note that you decided 
the number by subtracting each of his digit from 9. 
Thus, you now have.....
57836
37589
62410
54732
45267
Next, ask him to add all the number and he gets 257834
Show him the number which you had written as an answer 
to this addition earlier in the folded paper and surprise him.

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Give the answer in a + bi form?

2 Answers