Math Problem Statement

Divide -2 by (4 - 3i) and write the answer as a complex number in standard form.

Solution

To solve 243i\frac{-2}{4 - 3i} and write the answer in standard form (as a+bia + bi), we need to eliminate the imaginary unit ii from the denominator by multiplying both the numerator and the denominator by the conjugate of the denominator.

  1. Identify the conjugate: The conjugate of 43i4 - 3i is 4+3i4 + 3i.

  2. Multiply both numerator and denominator by the conjugate:

    243i×4+3i4+3i=2(4+3i)(43i)(4+3i)\frac{-2}{4 - 3i} \times \frac{4 + 3i}{4 + 3i} = \frac{-2(4 + 3i)}{(4 - 3i)(4 + 3i)}

  3. Expand the numerator:

    2(4+3i)=86i-2(4 + 3i) = -8 - 6i

    So the numerator becomes 86i-8 - 6i.

  4. Simplify the denominator using the difference of squares formula:

    (43i)(4+3i)=42(3i)2=169(1)=16+9=25(4 - 3i)(4 + 3i) = 4^2 - (3i)^2 = 16 - 9(-1) = 16 + 9 = 25

  5. Combine:

    86i25=825625i\frac{-8 - 6i}{25} = -\frac{8}{25} - \frac{6}{25}i

So the answer in standard form is:

825625i-\frac{8}{25} - \frac{6}{25}i

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


Here are some related questions to deepen understanding:

  1. How do you find the conjugate of a complex number?
  2. Why is multiplying by the conjugate helpful in simplifying complex fractions?
  3. What does it mean to express a complex number in standard form?
  4. How do you add and subtract complex numbers?
  5. How do you multiply two complex numbers?

Tip: When dividing by a complex number, always look for its conjugate to simplify the division into real and imaginary parts.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Division of Complex Numbers
Standard Form

Formulas

Conjugate of a complex number
Standard form a + bi

Theorems

Difference of squares for complex conjugates

Suitable Grade Level

Grades 10-12