CSCAPrep
Reviewed CSCA Mathematics question · Easy

What is the product (2 + 3i)(1 - i)?

  1. 5 + i
  2. 5 - i
  3. -1 + i
  4. 1 + 5i
Show the answer and explanation

Correct answer

A. 5 + i

Principle or equation

Multiply complex numbers using the distributive property (FOIL) and use i^2 = -1.

Why this answer is correct

(2 + 3i)(1 - i) = 2*1 + 2*(-i) + 3i*1 + 3i*(-i) = 2 - 2i + 3i - 3i^2 = 2 + i - 3(-1) = 2 + i + 3 = 5 + i.

Example

(1 + i)(1 - i) = 1 - i^2 = 1 - (-1) = 2.

This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.

Related practice questions

Standard · Geometry and algebraWhat is the center of the circle given by x^2 + y^2 - 4x + 6y - 3 = 0?Easy · Geometry and algebraGiven vectors u = (3, -2) and v = (1, 4), what is 2u - v?Easy · Geometry and algebraA rectangular box has vertices at (0,0,0), (4,0,0), (0,3,0), and (0,0,12). What is the length of the space diagonal of this box?Standard · Geometry and algebraWhat is the value of (3 + 2i) / (1 - i)?Easy · Geometry and algebraA cube has vertices at (0,0,0), (2,0,0), (0,2,0), and (0,0,2). What is the distance from the origin to the center of the…