Find the Domain of y=(x-5)²: Analyzing Positive and Negative Inputs

Quadratic Functions with Domain Analysis

Find the positive and negative domains of the function below:

y=(x5)2 y=\left(x-5\right)^2

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Find the positive and negative domains of the function below:

y=(x5)2 y=\left(x-5\right)^2

2

Step-by-step solution

To determine the positive and negative domains of the function y=(x5)2 y = (x - 5)^2 , follow these steps:

  • Step 1: Recognize the function is in vertex form: y=(xh)2+k y = (x - h)^2 + k , where the vertex is (h,k)=(5,0)(h, k) = (5, 0).
  • Step 2: Observe the properties of a square. The expression (x5)2 (x - 5)^2 is always greater than or equal to zero because a square of any real number cannot be negative.
  • Step 3: Analyze when the function is zero. The output y=0 y = 0 when x5=0 x - 5 = 0 , or x=5 x = 5 .
  • Step 4: Consider where y y is positive. For all x x except x=5 x = 5 , the square (x5)2>0 (x-5)^2 > 0 .
  • Step 5: Determine where y y is negative. Since a squared term is never negative, there are no values of x x for which y<0 y < 0 .

Based on these steps, the positive domain captures all x x except where x=5 x = 5 , and the negative domain is nonexistent because the square is always non-negative.

Therefore, the solution is:

x<0: x < 0 : none
x>0:x5 x > 0 : x\ne5

3

Final Answer

x<0: x < 0 : none
x>0:x5 x > 0 : x\ne5

Key Points to Remember

Essential concepts to master this topic
  • Domain Rule: Squared expressions are always non-negative for real numbers
  • Technique: Set (x5)2=0 (x-5)^2 = 0 to find where y equals zero
  • Check: Verify at x=5: (55)2=0 (5-5)^2 = 0 , at x=6: (65)2=1>0 (6-5)^2 = 1 > 0

Common Mistakes

Avoid these frequent errors
  • Confusing positive/negative domains with positive/negative x-values
    Don't think positive domain means x > 0 = wrong interpretation! The question asks where the function OUTPUT (y-values) is positive or negative, not the input x-values. Always focus on when y > 0 or y < 0.

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below does not intersect the \( x \)-axis.

The parabola's vertex is marked A.

Find all values of \( x \) where
\( f\left(x\right) > 0 \).

AAAX

FAQ

Everything you need to know about this question

What does 'positive domain' and 'negative domain' actually mean?

+

Positive domain: all x-values where the function output y>0 y > 0
Negative domain: all x-values where the function output y<0 y < 0
It's about the function's output, not whether x is positive or negative!

Why can't a squared expression be negative?

+

When you square any real number, the result is always positive or zero. For example: 32=9 3^2 = 9 and (3)2=9 (-3)^2 = 9 . Even 02=0 0^2 = 0 . There's no real number that gives a negative result when squared!

How do I find where the function equals zero?

+

Set the function equal to zero: (x5)2=0 (x-5)^2 = 0 . Since only zero squared equals zero, we need x5=0 x-5 = 0 , so x=5 x = 5 . This is the only point where the function touches the x-axis.

What does 'x ≠ 5' mean in the positive domain?

+

This means all real numbers except 5. At every x-value except x = 5, the function y=(x5)2 y = (x-5)^2 produces a positive output. At x = 5, the output is exactly zero, so it's neither positive nor negative.

Why is the answer format 'x < 0: none' and 'x > 0: x≠5'?

+

This notation is misleading but follows the question format. It should really say:
Negative domain (where y < 0): none
Positive domain (where y > 0): all x except x = 5
The 'x < 0' and 'x > 0' labels refer to the sign of the function output, not the input.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 The Quadratic Function questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations