Find the Domain of (x-2 1/9)² + 5/6: Positive and Negative Regions

Quadratic Functions with Vertex Form Analysis

Find the positive and negative domains of the function below:

y=(x219)2+56 y=\left(x-2\frac{1}{9}\right)^2+\frac{5}{6}

❤️ 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=(x219)2+56 y=\left(x-2\frac{1}{9}\right)^2+\frac{5}{6}

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Recognize that the given quadratic function is in vertex form y=(xh)2+k y = (x - h)^2 + k , where h=219 h = 2\frac{1}{9} and k=56 k = \frac{5}{6} .
  • Step 2: Identify that the squared term (x219)2 (x - 2\frac{1}{9})^2 is always non-negative for any real x x .
  • Step 3: Note that the smallest value that the squared term can obtain is 0, which happens when x=219 x = 2\frac{1}{9} . Therefore, the smallest value of the whole function y y is 56 \frac{5}{6} , which is positive. Thus, y y is never negative.
  • Step 4: Conclude by identifying the domains: y<0 y < 0 has no solutions and y>0 y > 0 for all x x .

After considering the nature of the quadratic function:

Since y y cannot be negative, the negative domain is none, which means there are no values where y<0 y < 0 .

On the other hand, for all x x , y y is positive because the minimum value y y can take is the constant term 56\frac{5}{6}, which is positive.

Thus, the solution is:

x<0: x < 0 : none

x>0: x > 0 : for all x x

3

Final Answer

x<0: x < 0 : none

x>0: x > 0 : for all x x

Key Points to Remember

Essential concepts to master this topic
  • Vertex Form: Function y=(xh)2+k y = (x - h)^2 + k has minimum value k
  • Technique: Since (x219)20 (x - 2\frac{1}{9})^2 \geq 0 , minimum y-value is 56 \frac{5}{6}
  • Check: At vertex x=219 x = 2\frac{1}{9} , we get y=56>0 y = \frac{5}{6} > 0

Common Mistakes

Avoid these frequent errors
  • Confusing domain with range or sign analysis
    Don't mix up finding where x-values exist (domain) with finding where y-values are positive/negative (range analysis)! The question asks for positive/negative regions of the function, not the domain. Always analyze the y-values: since the minimum is 56>0 \frac{5}{6} > 0 , y is always positive.

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 and negative domains' actually mean?

+

This is asking where the function output (y-values) is positive or negative, not about the domain of x-values. We need to find when y>0 y > 0 and when y<0 y < 0 .

How do I know the minimum value of this function?

+

In vertex form y=(xh)2+k y = (x - h)^2 + k , the minimum value is k because (xh)20 (x - h)^2 \geq 0 always. Here, k=56 k = \frac{5}{6} , so the minimum y-value is 56 \frac{5}{6} .

Why can't this function ever be negative?

+

Since the smallest possible value of the function is 56 \frac{5}{6} (which is positive), the function can never dip below zero. The parabola opens upward and its lowest point is above the x-axis!

What if the constant term was negative instead?

+

Great question! If k k were negative (like -2), then the minimum value would be negative, and the function could be both positive and negative depending on the x-value.

How do I convert the mixed number in the problem?

+

219=2+19=189+19=199 2\frac{1}{9} = 2 + \frac{1}{9} = \frac{18}{9} + \frac{1}{9} = \frac{19}{9} . But for this problem, you don't actually need to convert it - just recognize it as the vertex location!

🌟 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