Find the Domain of (x+10)²+2: Analyzing Positive and Negative Inputs

Quadratic Functions with Positive Range Analysis

Find the positive and negative domains of the function below:

y=(x+10)2+2 y=\left(x+10\right)^2+2

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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=(x+10)2+2 y=\left(x+10\right)^2+2

2

Step-by-step solution

The function given is y=(x+10)2+2 y = (x+10)^2 + 2 . This is a quadratic function in vertex form.

The vertex form of a quadratic function is y=a(xh)2+k y = a(x-h)^2 + k , where the vertex is (h,k)(h, k). For our function, h=10 h = -10 and k=2 k = 2 , so the vertex is (10,2)(-10, 2).

In this case, since the coefficient of (x+10)2(x+10)^2 is positive (implicitly 1), the parabola opens upwards. This means the function has a minimum point at the vertex, and y y will only increase from that point.

Given that the vertex point has a y y -value of 2, which is positive, the entire domain yields values of y y that are greater than 2. Therefore, y y will never be negative.

Now, let's determine the domains:

  • For the negative domain, we seek values of x x where the function y y is negative. Since the minimum y y -value is 2, no such x x satisfies y<0 y \lt 0 . Hence, there is no negative domain.
  • Similarly, all values of x x yield a positive range of y y , as y2 y \geq 2 for all x x . Thus, for the positive domain, it is all x x , as every y y value is positive or zero.

Consequently, the specified positive domain is all x x , and the negative domain is none.

Thus, the correct answer is:

x<0: x < 0 : None

x>0: x > 0 : All x x

3

Final Answer

x<0: x < 0 : None

x>0: x > 0 : All x x

Key Points to Remember

Essential concepts to master this topic
  • Rule: Upward parabolas with positive vertex have positive output values
  • Technique: Find vertex at (-10, 2) from y=(x+10)2+2 y = (x+10)^2 + 2
  • Check: Minimum y-value is 2 > 0, so no negative outputs exist ✓

Common Mistakes

Avoid these frequent errors
  • Confusing input domains with output values
    Don't think negative x-values create a negative domain = wrong interpretation! The domain refers to x-values that make y negative or positive, not the sign of x itself. Always check whether the function output y is positive or negative, regardless of input sign.

Practice Quiz

Test your knowledge with interactive questions

The graph of the function below intersects the X-axis at points A and B.

The vertex of the parabola is marked at point C.

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

AAABBBCCCX

FAQ

Everything you need to know about this question

What does 'positive domain' actually mean?

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The positive domain means all x-values where the function gives positive y-values. It's not about whether x is positive or negative - it's about whether y>0 y > 0 !

Why is the vertex important for this problem?

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The vertex (10,2) (-10, 2) gives the minimum point of this upward parabola. Since the lowest y-value is 2 (which is positive), all other y-values are even more positive!

How can I tell if a parabola opens upward or downward?

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Look at the coefficient of the squared term. In y=(x+10)2+2 y = (x+10)^2 + 2 , the coefficient is +1 (positive), so it opens upward like a smile!

Could there ever be a negative domain for this function?

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No! Since the minimum y-value is 2, and 2>0 2 > 0 , this function never produces negative outputs. The negative domain is empty (none).

What if the vertex had a negative y-coordinate?

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Then you'd need to solve (x+10)2+k=0 (x+10)^2 + k = 0 to find where y becomes negative. But since our vertex has y = 2 > 0, this never happens.

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