SOLUTION: Solve, Conjugate(z) - 12/z = 1-i, expressing your answer in the form a + ib where a and b are real numbers. [4 marks]

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Solve, Conjugate(z) - 12/z = 1-i, expressing your answer in the form a + ib where a and b are real numbers. [4 marks]      Log On


   



Question 1152633: Solve, Conjugate(z) - 12/z = 1-i, expressing your answer in the form a + ib where a and b are real numbers. [4 marks]
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Conjugate%28z%29+-+12%2Fz+=+1-i

Let z = x+yi, where x and y are real numbers

Conjugate%28x%2Byi%29+-+12%2F%28x%2Byi%29+=+1-i

%28x-yi%29+-+%2812%2F%28x%2Byi%29%29%28%28x-yi%29%2F%28x-yi%29%29+=+1-i

x-yi+-+%2812x-12yi%5E%22%22%29%2F%28x%5E2-y%5E2i%5E2%29+=+1-i

i² = -1

x-yi+-+%2812x-12yi%5E%22%22%29%2F%28x%5E2-y%5E2%28-1%29%29+=+1-i

x-yi+-+%2812x-12yi%5E%22%22%29%2F%28x%5E2%2By%5E2%29+=+1-i

Put parentheses around the fraction term:

x-yi+-+%28%2812x-12yi%5E%22%22%29%2F%28x%5E2%2By%5E2%29%29+=+1-i

Break the fraction term into two fractions:



Remove the parentheses:



In an equation with both real and imaginary terms, the real
and imaginary terms are like oil and water. The real terms
on the left equals the real terms on the right, and the 
imaginary terms on the left equal the imaginary terms on the
right.  So we split it into two equations.

The REAL equation is:

x-+%2812x%5E%22%22%29%2F%28x%5E2%2By%5E2%29+=+1

The IMAGINARY equation is

-yi%2B%2812yi%5E%22%22%29%2F%28x%5E2%2By%5E2%29+=+-i

which we divide through by -i

y-%2812y%5E%22%22%29%2F%28x%5E2%2By%5E2%29+=+1

So we have the system of equations:



The equations are symmetrical in x and y.  So we can substitute 
x for y.  

x-+%2812x%5E%22%22%29%2F%28x%5E2%2By%5E2%29+=+1

Replace y by x:

x-+%2812x%5E%22%22%29%2F%28x%5E2%2Bx%5E2%29+=+1

x-+%2812x%5E%22%22%29%2F%282x%5E2%29+=+1

x-+6%2Fx+=+1

x%5E2-6+=+x

x%5E2-x-6=0

%28x-3%29%28x%2B2%29=0

x - 3 = 0; x + 2 = 0
    x = 3;     x = -2

So there are two solutions: (x,y) = (3,3), (x,y) = (-2,-2)

Expressing in a+bi form:

z = x+yi = 3+3i   and  z = x+yi = -2-2i

Edwin