Math Problem Statement

Graph the complex number.

9 + 8i

The complex plane is given. The horizontal axis is labeled "Re" and the vertical axis is labeled "Im". A point (9, −8) is graphed.

The complex plane is given. The horizontal axis is labeled "Re" and the vertical axis is labeled "Im". A point (8, 9) is graphed.

The complex plane is given. The horizontal axis is labeled "Re" and the vertical axis is labeled "Im". A point (9, 8) is graphed.

The complex plane is given. The horizontal axis is labeled "Re" and the vertical axis is labeled "Im". A point (−9, 8) is graphed.

Find the modulus r.

r =

Solution

The complex number given is 9+8i9 + 8i.

Step 1: Locate the Point on the Complex Plane

In this case:

  • The real part (Re\text{Re}) is 99.
  • The imaginary part (Im\text{Im}) is 88.

So, the point on the complex plane is (9,8)(9, 8).

Thus, the correct answer for the location of the point on the complex plane is:

  • The complex plane is given. The horizontal axis is labeled "Re" and the vertical axis is labeled "Im". A point (9, 8) is graphed.

Step 2: Find the Modulus rr

The modulus rr of a complex number a+bia + bi is given by the formula: r=a2+b2r = \sqrt{a^2 + b^2}

For 9+8i9 + 8i: r=92+82=81+64=145r = \sqrt{9^2 + 8^2} = \sqrt{81 + 64} = \sqrt{145}

So, the modulus rr is: r=14512.04r = \sqrt{145} \approx 12.04

If you'd like more details or have any questions, feel free to ask!


Here are some additional questions to deepen your understanding:

  1. What is the argument (angle) of this complex number on the complex plane?
  2. How do you graph complex numbers with negative imaginary parts?
  3. How does the modulus change if the complex number is 98i-9 - 8i?
  4. What is the relationship between the modulus and distance from the origin?
  5. How would the complex number look in polar form?

Tip: The modulus of a complex number tells you how far the point is from the origin on the complex plane.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Graphing in the Complex Plane
Modulus of Complex Numbers

Formulas

Modulus of a complex number r = sqrt(a^2 + b^2) for a complex number a + bi

Theorems

Pythagorean Theorem (used in modulus calculation)

Suitable Grade Level

Grades 9-12