Exploring the Domain of the Function: √(4x² - 8)/5

Question

Look at the following function:

4x285 \frac{\sqrt{4x^2-8}}{5}

What is the domain of the function?

Video Solution

Solution Steps

00:00 Does the function have a domain of definition? And if so, what is it?
00:04 The denominator domain is to prevent division by 0
00:07 Therefore, for the denominator there is no domain restriction, let's check the numerator
00:12 A square root must be of a positive number
00:18 We'll set it equal to 0 to find the solutions
00:21 We'll isolate X
00:32 When finding a square root, there are always 2 solutions, positive and negative
00:38 Let's draw to find the domain of definition
00:46 Between the solutions, any value of X necessarily creates a negative root
00:53 And this is the solution to the question

Step-by-Step Solution

To determine the domain of the function 4x285 \frac{\sqrt{4x^2 - 8}}{5} , we must ensure the expression under the square root is non-negative. This condition will make the function well-defined over the real numbers.

Steps to solve for the domain:

  • Step 1: Set the expression inside the square root greater or equal to zero: 4x280 4x^2 - 8 \geq 0 .
  • Step 2: Solve the inequality.

To solve the inequality 4x280 4x^2 - 8 \geq 0 :

Step 3: Add 8 to both sides:

4x28 4x^2 \geq 8

Step 4: Divide each term by 4 to simplify:

x22 x^2 \geq 2

Step 5: Solve for x x . When an inequality involves a square, interpret it as involving two cases. Thus, x2 x \geq \sqrt{2} OR x2 x \leq -\sqrt{2} .

This inequality describes the values of x x for which the function is defined. These constitute the domain of the function. Therefore, the domain is x2 x \geq \sqrt{2} or x2 x \leq -\sqrt{2} .

The correct answer choice is:

x2,x2 x\ge\sqrt{2},x\le-\sqrt{2}

Answer

x2,x2 x\ge\sqrt{2},x\le-\sqrt{2}