![Bailey1116680](/avatars/8951.jpg)
Bailey1116680
02.10.2019 •
Mathematics
When a complex number is in the denominator, why is it necessary to multiply by the conjugate?
Solved
Show answers
More tips
- F Family and Home How to Teach Your Child to Read?...
- C Computers and Internet How to Download Videos from YouTube? Simple Steps to Download Any Content...
- S Style and Beauty Tricks and Tips: How to Get Rid of Freckles...
- H Health and Medicine How to perform artificial respiration?...
- C Computers and Internet How to Get Rid of Windows Genuine Check?...
- F Food and Cooking The Disease That Haunted Abraham Lincoln...
- S Style and Beauty How to Make Your Lips Fuller? Ideas and Tips for Beautiful Lips...
- S Style and Beauty How are artificial nails removed?...
- F Family and Home How to Sew Curtain Tapes: Best Tips from Professionals...
- H Horoscopes, Magic, Divination How to Cast a Love Spell on a Guy? Guide for Guys...
Answers on questions: Mathematics
- M Mathematics 67/8+87*432 = 86/7+76*321 This person is really getting on my nerves ;-;...
- M Mathematics The grid shows the positions of a subway stop in your house does subway stop is located at The grid shows the positions of a subway stop in your house does subway stop is located...
- M Mathematics Please help me with this real quick....
- M Mathematics True or false. if a is any odd integer, then a^2 + a is even. explain this....
- M Mathematics Can someone help me find area of triangle ABC please. ac is equal to 12.5 cm. i just need the area please explain thank u...
- H History HELPP ME WITH THIS PLEASE- 4 and 5!!...
Ответ:
For the general complex number (a + bi), its conjugate is (a - bi).
By definition, i² = -1.
Evaluate (a + bi)*(a - bi) to obtain
(a + bi)*(a - bi) = a² - abi + abi - b²i²
= a² - b²*(-1)
= a² + b²
This means that multiplying a complex number by its conjugate yields a real number.
For this reason, it is customary to make the denominator of a complex rational expression into a real number, by multiplying the denominator by its conjugate.
Of course, the numerator should also be multiplied by the same conjugate.
Example:
Simplify (2 - 3i)/(1 + 4i) into the form a + bi.
The denominator is (1 + 4i) and its conjugate is (1 - 4i).
Multiply the denominator by its conjugate to obtain
(1 + 4i)*(1 - 4i) =1² + 4² = 17.
Also, multiply the numerator by the same conjugate to obtain
(2 - 3i)*(1 - 4i) = 2 - 8i - 3i + (3i)*(4i)
= 2 - 11i + 12*i²
= 2 - 11i - 12
= -10 - 11i
Therefore
(2 - 3i)/(1 + 4i) = -(10 + 11i)/17
Ответ: