Math Problem Statement

Divide. StartFraction 2 plus i Over 2 minus i EndFraction 2+i 2−i

Solution

To divide the complex numbers 2+i2i\frac{2 + i}{2 - i}, we use the method of multiplying by the conjugate of the denominator. The conjugate of 2i2 - i is 2+i2 + i. Here's the step-by-step process:

  1. Multiply the numerator and the denominator by the conjugate of the denominator: 2+i2i×2+i2+i=(2+i)×(2+i)(2i)×(2+i)\frac{2 + i}{2 - i} \times \frac{2 + i}{2 + i} = \frac{(2 + i) \times (2 + i)}{(2 - i) \times (2 + i)}

  2. Expand the numerator and the denominator:

    • Numerator: (2+i)×(2+i)=22+2×2×i+i2=4+4i+i2(2 + i) \times (2 + i) = 2^2 + 2 \times 2 \times i + i^2 = 4 + 4i + i^2 Since i2=1i^2 = -1: 4+4i+(1)=3+4i4 + 4i + (-1) = 3 + 4i

    • Denominator: (2i)×(2+i)=22(i)2=4(1)=4+1=5(2 - i) \times (2 + i) = 2^2 - (i)^2 = 4 - (-1) = 4 + 1 = 5

  3. Combine the results: 3+4i5\frac{3 + 4i}{5}

  4. Separate into real and imaginary parts: 3+4i5=35+4i5\frac{3 + 4i}{5} = \frac{3}{5} + \frac{4i}{5}

So, the final result is: 2+i2i=35+4i5\frac{2 + i}{2 - i} = \frac{3}{5} + \frac{4i}{5}

Would you like more details or have any questions about this process?

Here are 5 related questions to expand your understanding:

  1. How do you find the conjugate of a complex number?
  2. What is the significance of multiplying by the conjugate when dividing complex numbers?
  3. Can you explain why i2=1i^2 = -1 and how it affects complex number multiplication?
  4. How do you add and subtract complex numbers?
  5. What is the geometric interpretation of complex number division?

Tip: When dividing complex numbers, multiplying by the conjugate helps eliminate the imaginary part in the denominator, simplifying the expression to a standard form.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Division of Complex Numbers
Conjugates

Formulas

Multiply by the conjugate: \(\frac{a+bi}{c+di} \times \frac{c-di}{c-di}\)
i^2 = -1

Theorems

Conjugate Method for Complex Division

Suitable Grade Level

Grades 9-12