Positive and Negativity of a Linear Function

🏆Practice positivity and negativity

Positivity and Negativity of a Linear Function

The function is positive when it is above the X X axis when Y<0 Y<0

The function is negative when it is below the X X axis as Y>0 Y>0

When we are asked what the domains of positivity of the function are, we are actually being asked in which values of X X the function is positive: when it is above the X X axis.

In which values of X X does the function obtain positive Y Y values?

When we are asked what the domain of negativity of the function is, we are actually being asked in which values of X X the function is negative: when it is below the X X axis.

In which values of X X does the function obtain negative Y Y values?

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Test yourself on positivity and negativity!

einstein

Look at the linear function represented in the diagram.

When is the function positive?

–8–8–8–7–7–7–6–6–6–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333444555666777888–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000

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Now, we will see an example in which we find the domain of positivity and negativity of the function by solving an inequality:

Let's see an example in which we find the domains of positivity and negativity of the function through a graph:

Let's observe the point of intersection of the function with the axis :X X

Given the function: y=4x2 y=4x-2

What is the domain of positivity and what is the domain of negativity of the function?

Let's remember that when we are asked about the domain of positivity, we are asked in which values of X X , the values of Y Y are positive.

Therefore, when Y>0 Y>0

We will take the equation equal to Y Y

4X2 4X-2

And check when it is greater than 0 0

4X2>0 4X-2>0

We solve the inequality:

4X>2 4X>2

X>0.5 X>0.5

The domain of positivity of the line is:

X>0.5 X>0.5

Now let's remember that when we are asked about the domain of negativity, we are asked in which values of X X , the values of Y Y are negative.

Therefore, whenY<0 Y<0

We will take the equation equal toY Y

4X2 4X-2

And check when it is less than 0 0

4X2<0 4X-2<0

We solve the inequality:

4X<2 4X<2

X<0.5 X<0.5

The domain of negativity of the line is:

X<0.5 X<0.5


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