124k views
25 votes
Simplify. 1+i/1-I + 1/ 1 + i. if i^2 = -1

User Svitlana
by
7.6k points

1 Answer

12 votes

I guess you mean

(1 + i ) / (1 - i ) + 1 / (1 + i )

in which case, notice that the denominator of both fractions are conjugates of one another. Combine the fractions by multiplying either fraction by the appropriate conjugate:

[(1 + i ) / (1 - i ) • (1 + i ) / (1 + i )]+ [1 / (1 + i ) • (1 - i ) / (1 - i )]

In either denominator, we have a difference of squares:

(1 + i ) (1 - i ) = 1² + i - i - i ² = 1² - i ² = 1 + 1 = 2

→ (1 + i )² / 2 + (1 - i ) / 2

→ ((1 + i )² + (1 - i )) / 2

Expand the numerator:

(1 + i )² + (1 - i ) = (1² + 2i + i ²) + 1 - i = 1 + 2 - 1 + 1 - i = 3 - i

and so

(1 + i ) / (1 - i ) + 1 / (1 + i ) = (3 - i ) / 2

User Aguid
by
9.0k points