Math Problem Statement

Find the square root of βˆ’48 βˆ’ 14𝑖. (in standard form)

Solution

To find the square root of the complex number βˆ’48βˆ’14i-48 - 14i, we will express the result in the standard form a+bia + bi, where aa and bb are real numbers.

Let's go through the steps:

  1. Set up the equation: βˆ’48βˆ’14i=a+bi\sqrt{-48 - 14i} = a + bi where aa and bb are real numbers.

  2. Square both sides: (a+bi)2=βˆ’48βˆ’14i(a + bi)^2 = -48 - 14i Expanding the left side using the identity (a+bi)2=a2βˆ’b2+2abi(a + bi)^2 = a^2 - b^2 + 2abi, we get: a2βˆ’b2+2abi=βˆ’48βˆ’14ia^2 - b^2 + 2abi = -48 - 14i

  3. Equate real and imaginary parts: From the above, equate the real and imaginary parts separately:

    • Real part: a2βˆ’b2=βˆ’48a^2 - b^2 = -48
    • Imaginary part: 2ab=βˆ’142ab = -14
  4. Solve the system of equations:

    From the imaginary part equation 2ab=βˆ’142ab = -14, we can solve for abab: ab=βˆ’7ab = -7

    Now, substitute b=βˆ’7ab = -\frac{7}{a} into the real part equation: a2βˆ’(βˆ’7a)2=βˆ’48a^2 - \left( -\frac{7}{a} \right)^2 = -48 Simplify: a2βˆ’49a2=βˆ’48a^2 - \frac{49}{a^2} = -48

    Multiply both sides by a2a^2 to eliminate the fraction: a4+48a2βˆ’49=0a^4 + 48a^2 - 49 = 0

    Let x=a2x = a^2, so we have the quadratic equation: x2+48xβˆ’49=0x^2 + 48x - 49 = 0

  5. Solve the quadratic equation: Using the quadratic formula: x=βˆ’48Β±482βˆ’4(1)(βˆ’49)2(1)x = \frac{-48 \pm \sqrt{48^2 - 4(1)(-49)}}{2(1)} Simplify: x=βˆ’48Β±2304+1962x = \frac{-48 \pm \sqrt{2304 + 196}}{2} x=βˆ’48Β±25002x = \frac{-48 \pm \sqrt{2500}}{2} x=βˆ’48Β±502x = \frac{-48 \pm 50}{2} So, x=βˆ’48+502=1orx=βˆ’48βˆ’502=βˆ’49x = \frac{-48 + 50}{2} = 1 \quad \text{or} \quad x = \frac{-48 - 50}{2} = -49 Since x=a2β‰₯0x = a^2 \geq 0, we discard x=βˆ’49x = -49 and take x=1x = 1. Therefore, a2=1a^2 = 1, so a=1a = 1 or a=βˆ’1a = -1.

  6. Find bb: Using ab=βˆ’7ab = -7 and a=1a = 1 or a=βˆ’1a = -1, we can find bb:

    • If a=1a = 1, then b=βˆ’7b = -7.
    • If a=βˆ’1a = -1, then b=7b = 7.
  7. Final solution: Therefore, the square roots of βˆ’48βˆ’14i-48 - 14i are: 1βˆ’7iorβˆ’1+7i\boxed{1 - 7i \quad \text{or} \quad -1 + 7i}

Would you like more details on any step, or further clarification?


Here are 5 related questions:

  1. How do you determine the polar form of a complex number?
  2. What is the geometric interpretation of the square root of a complex number?
  3. How can we apply De Moivre’s Theorem to find roots of complex numbers?
  4. How does the discriminant in quadratic equations affect the nature of roots?
  5. What are the applications of complex numbers in physics and engineering?

Tip: When solving for square roots of complex numbers, expressing them in polar form can sometimes simplify the process!

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Quadratic Equations
Algebraic Manipulation

Formulas

(a + bi)^2 = a^2 - b^2 + 2abi
Quadratic Formula: x = [-b Β± sqrt(b^2 - 4ac)] / 2a

Theorems

Quadratic Formula
Properties of Complex Numbers

Suitable Grade Level

Grades 10-12