Math  /  Algebra

QuestionIf zz is the solution of the equation: z1+i=2izz-1+i=2 i z then Re(z)=\operatorname{Re}(z)= Note: Answer should be in decimal form (do not use fraction)

Studdy Solution

STEP 1

What is this asking? Find the real part of the complex number zz that solves the equation z1+i=2izz - 1 + i = 2iz. Watch out! Remember that zz is a complex number, so we can't just treat it like a regular variable.
We'll need to carefully isolate zz and consider its real and imaginary parts separately.

STEP 2

1. Isolate zz
2. Find the real part of zz

STEP 3

We start with our given equation: z1+i=2iz z - 1 + i = 2iz Let's **move** all the terms with zz to one side and the other terms to the other side.
We'll add 1 and subtract ii from both sides, and also subtract 2iz2iz from both sides: z2iz=1i z - 2iz = 1 - i

STEP 4

On the left side, we can **factor out** zz: z(12i)=1i z(1 - 2i) = 1 - i

STEP 5

Now, we want to **isolate** zz, so we'll **divide** both sides by (12i)(1 - 2i): z=1i12i z = \frac{1 - i}{1 - 2i}

STEP 6

To simplify this complex fraction, we'll **multiply** the numerator and denominator by the **conjugate** of the denominator, which is (1+2i)(1 + 2i).
This will give us a real number in the denominator: z=1i12i1+2i1+2i z = \frac{1 - i}{1 - 2i} \cdot \frac{1 + 2i}{1 + 2i}

STEP 7

**Expanding** the numerator, we get: (1i)(1+2i)=1+2ii2i2=1+i2(1)=1+i+2=3+i (1 - i)(1 + 2i) = 1 + 2i - i - 2i^2 = 1 + i - 2(-1) = 1 + i + 2 = 3 + i **Expanding** the denominator, we get: (12i)(1+2i)=1+2i2i4i2=14(1)=1+4=5 (1 - 2i)(1 + 2i) = 1 + 2i - 2i - 4i^2 = 1 - 4(-1) = 1 + 4 = 5 So, z=3+i5 z = \frac{3 + i}{5}

STEP 8

We can **rewrite** this as: z=35+15i z = \frac{3}{5} + \frac{1}{5}i

STEP 9

The real part of zz is the coefficient of the term without ii, which is 35\frac{3}{5}.
As a decimal, this is **0.6**.

STEP 10

The real part of zz, or Re(z)\operatorname{Re}(z), is **0.6**.

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