Math Problem Statement

In the picture it is Complex Variables and Transforms, now slove the equation as given in picture

Define complex number and its modulus and argument. Find the modulus and principal argument of (2 - 5i)(3 - i) / (1 - 2i)^2.

Solution

The problem in the image asks to define a complex number and its modulus and argument, then find the modulus and principal argument of the expression:

(25i)(3i)(12i)2\frac{(2 - 5i)(3 - i)}{(1 - 2i)^2}

Step 1: Simplify the expression

We will first simplify the expression by multiplying the numerators and expanding the denominator.

Numerator:

= 6 - 2i - 15i + 5i^2$$ Since $$i^2 = -1$$, the above becomes: $$6 - 17i + 5(-1) = 6 - 17i - 5 = 1 - 17i$$ So, the numerator simplifies to $$1 - 17i$$. #### Denominator: $$(1 - 2i)^2 = (1 - 2i)(1 - 2i) = 1 \times 1 + 1 \times (-2i) + (-2i) \times 1 + (-2i) \times (-2i) = 1 - 2i - 2i + 4i^2$$ Again, using $$i^2 = -1$$, we get: $$1 - 4i - 4 = -3 - 4i$$ So, the expression simplifies to: $$\frac{1 - 17i}{-3 - 4i}$$ ### Step 2: Convert to polar form To find the modulus and argument, we need to convert the expression to polar form. #### Modulus: The modulus of a complex number $$z = a + bi$$ is given by: $$|z| = \sqrt{a^2 + b^2}$$ For the numerator $$1 - 17i$$: $$|1 - 17i| = \sqrt{1^2 + (-17)^2} = \sqrt{1 + 289} = \sqrt{290}$$ For the denominator $$-3 - 4i$$: $$|-3 - 4i| = \sqrt{(-3)^2 + (-4)^2} = \sqrt{9 + 16} = \sqrt{25} = 5$$ Thus, the modulus of the whole expression is: $$\frac{\sqrt{290}}{5}$$ #### Argument: The argument of a complex number $$z = a + bi$$ is given by: $$\arg(z) = \tan^{-1}\left(\frac{b}{a}\right)$$ For the numerator $$1 - 17i$$, we get: $$\arg(1 - 17i) = \tan^{-1}\left(\frac{-17}{1}\right) = \tan^{-1}(-17)$$ For the denominator $$-3 - 4i$$, we get: $$\arg(-3 - 4i) = \tan^{-1}\left(\frac{-4}{-3}\right) = \tan^{-1}\left(\frac{4}{3}\right)$$ The total argument is: $$\arg\left(\frac{1 - 17i}{-3 - 4i}\right) = \arg(1 - 17i) - \arg(-3 - 4i)$$ Now, let's calculate these values numerically.The results for the expression $$\frac{(2 - 5i)(3 - i)}{(1 - 2i)^2}$$ are: - **Modulus**: $$\approx 3.41$$ - **Principal argument**: $$\approx 0.702$$ radians (or $$\approx 40.24^\circ$$) Would you like more details on any of the steps? Here are some related questions you might explore: 1. How can we use polar form to multiply and divide complex numbers? 2. What are the geometric interpretations of modulus and argument? 3. How can we find the argument of a complex number when the real part is negative? 4. What role does the principal value of the argument play in complex number operations? 5. Can the modulus of a complex number ever be negative? **Tip:** Always make sure to express the argument in radians or degrees based on the context, and use the principal value between $$-\pi$$ and $$\pi$$ radians.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Modulus
Argument
Polar Form

Formulas

Modulus: |z| = √(a^2 + b^2)
Argument: arg(z) = tan^(-1)(b/a)

Theorems

Properties of Complex Numbers

Suitable Grade Level

Grades 11-12