Math Problem Statement

(-1-I)^9 + (-4+2I)^6

Solution

Let's solve (1i)9+(4+2i)6(-1 - i)^9 + (-4 + 2i)^6 step-by-step.

Step 1: Compute (1i)9(-1 - i)^9

  1. Convert 1i-1 - i to polar form. First, find the modulus and argument:

    • The modulus rr is 1i=(1)2+(1)2=2| -1 - i | = \sqrt{(-1)^2 + (-1)^2} = \sqrt{2}.
    • The argument θ\theta (in radians) is arctan(11)π=3π4\arctan\left(\frac{-1}{-1}\right) - \pi = -\frac{3\pi}{4} since the point is in the third quadrant.
  2. In polar form, 1i=2ei(3π4)-1 - i = \sqrt{2} \cdot e^{i \cdot (-\frac{3\pi}{4})}.

  3. Raise this to the power 9: (1i)9=(2ei(3π4))9=(2)9ei(27π4)(-1 - i)^9 = \left(\sqrt{2} \cdot e^{i \cdot (-\frac{3\pi}{4})}\right)^9 = (\sqrt{2})^9 \cdot e^{i \cdot (-\frac{27\pi}{4})}

    • Simplify the modulus: (2)9=24.5=162(\sqrt{2})^9 = 2^{4.5} = 16\sqrt{2}.
    • For the argument, reduce 27π4-\frac{27\pi}{4} to an equivalent angle within [0,2π)[0, 2\pi): 27π4+7π=5π4-\frac{27\pi}{4} + 7\pi = \frac{5\pi}{4}.

    Therefore: (1i)9=162ei5π4(-1 - i)^9 = 16\sqrt{2} \cdot e^{i \cdot \frac{5\pi}{4}} In rectangular form: =1616i= -16 - 16i

Step 2: Compute (4+2i)6(-4 + 2i)^6

  1. Convert 4+2i-4 + 2i to polar form. First, find the modulus and argument:

    • The modulus rr is 4+2i=(4)2+22=20=25| -4 + 2i | = \sqrt{(-4)^2 + 2^2} = \sqrt{20} = 2\sqrt{5}.
    • The argument θ\theta is arctan(24)+π=π2\arctan\left(\frac{2}{-4}\right) + \pi = \frac{\pi}{2} (second quadrant).
  2. In polar form, 4+2i=25eiπ2-4 + 2i = 2\sqrt{5} \cdot e^{i \cdot \frac{\pi}{2}}.

  3. Raise this to the power 6: (4+2i)6=(25eiπ2)6=(25)6ei3π(-4 + 2i)^6 = \left(2\sqrt{5} \cdot e^{i \cdot \frac{\pi}{2}}\right)^6 = (2\sqrt{5})^6 \cdot e^{i \cdot 3\pi}

    • Simplify the modulus: (25)6=4000(2\sqrt{5})^6 = 4000.
    • For the argument, 3π3\pi is equivalent to π\pi (mod 2π2\pi).

    Therefore: (4+2i)6=4000eiπ=4000(-4 + 2i)^6 = 4000 \cdot e^{i \cdot \pi} = -4000

Step 3: Add the Results

Now we add the two results: (1i)9+(4+2i)6=(1616i)+(4000)=401616i(-1 - i)^9 + (-4 + 2i)^6 = (-16 - 16i) + (-4000) = -4016 - 16i

Final Answer

401616i\boxed{-4016 - 16i}

Would you like further details on any step, or do you have questions?


Here are five related questions to practice:

  1. What is the polar form of 1+i1 + i?
  2. How would you simplify (3+4i)4(3 + 4i)^4?
  3. Can you express 2i-2i in polar form and raise it to a power?
  4. What is the modulus of 3+33i-3 + 3\sqrt{3}i?
  5. How do you convert a complex number in polar form to rectangular form?

Tip: When converting arguments, ensure they fall within the principal range [0,2π)[0, 2\pi) or (π,π](-\pi, \pi] for consistency.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form Conversion
Exponentiation of Complex Numbers
Rectangular Form Conversion

Formulas

Modulus of a complex number: |a + bi| = sqrt(a^2 + b^2)
Argument of a complex number in polar form
De Moivre's Theorem: (r * e^(iθ))^n = r^n * e^(inθ)

Theorems

De Moivre's Theorem

Suitable Grade Level

Undergraduate level