Math Problem Statement

z = (1 + i)^{10}

Solution

The given expression is z=(1+i)10z = (1 + i)^{10}, where ii is the imaginary unit, defined as i2=1i^2 = -1.

To solve this, we can follow these steps:

Step 1: Convert to Polar Form

The complex number 1+i1 + i can be converted to polar form. For a complex number z=a+biz = a + bi, its polar form is given by: z=r(cosθ+isinθ)z = r \left( \cos \theta + i \sin \theta \right) where rr is the modulus and θ\theta is the argument.

For 1+i1 + i:

  • r=12+12=2r = \sqrt{1^2 + 1^2} = \sqrt{2}
  • θ=tan1(11)=π4\theta = \tan^{-1} \left( \frac{1}{1} \right) = \frac{\pi}{4}

So, in polar form: 1+i=2(cosπ4+isinπ4)1 + i = \sqrt{2} \left( \cos \frac{\pi}{4} + i \sin \frac{\pi}{4} \right)

Step 2: Apply De Moivre's Theorem

De Moivre's Theorem states that for any complex number in polar form r(cosθ+isinθ)r(\cos \theta + i \sin \theta), raising it to the power of nn results in: (r(cosθ+isinθ))n=rn(cos(nθ)+isin(nθ))\left( r \left( \cos \theta + i \sin \theta \right) \right)^n = r^n \left( \cos (n\theta) + i \sin (n\theta) \right)

Thus, applying this to (1+i)10(1 + i)^{10}: (1+i)10=(2)10(cos(10×π4)+isin(10×π4))(1 + i)^{10} = \left( \sqrt{2} \right)^{10} \left( \cos \left( 10 \times \frac{\pi}{4} \right) + i \sin \left( 10 \times \frac{\pi}{4} \right) \right)

Step 3: Simplify

  • (2)10=25=32\left( \sqrt{2} \right)^{10} = 2^5 = 32
  • 10×π4=10π4=5π210 \times \frac{\pi}{4} = \frac{10\pi}{4} = \frac{5\pi}{2}

Now, simplify the trigonometric expressions:

  • cos5π2=cosπ2=0\cos \frac{5\pi}{2} = \cos \frac{\pi}{2} = 0
  • sin5π2=sinπ2=1\sin \frac{5\pi}{2} = \sin \frac{\pi}{2} = 1

Thus: z=32(0+i1)=32iz = 32 (0 + i \cdot 1) = 32i

Final Answer:

z=32iz = 32i

Would you like any further explanation or details?

Here are some related questions:

  1. How do you convert any complex number to polar form?
  2. What is the significance of De Moivre's theorem in complex numbers?
  3. How can you find the argument of a complex number geometrically?
  4. What are other applications of polar forms in mathematics?
  5. Can you visualize 1+i1 + i and 32i32i on the complex plane?

Tip: When solving powers of complex numbers, converting them into polar form often simplifies the process greatly.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form
Exponents

Formulas

Polar Form of Complex Numbers: z = r(cos θ + i sin θ)
De Moivre's Theorem: (r(cos θ + i sin θ))^n = r^n(cos(nθ) + i sin(nθ))

Theorems

De Moivre's Theorem

Suitable Grade Level

Grades 10-12