Positivity and Negativity: Finding a linear equation using positive and negative domains

Which equation represents a line that is positive in domain for each value of x.

To find out if the equation intersects the x-axis, we need to substitute y=0 in each equation.
If the function has a solution where y=0 then the equation has an intersection point and is not the correct answer.

Let's start with the first equation:

y = 3x+8

We will substitute as instructed:

0 = 3x+8

3x = -8

x = -8/3

Although the result here is not a "nice" number, we see that we are able to arrive at a result and therefore this answer is rejected.

Let's move on to the second equation:

y = 300x+50

Here too we will substitute:

0 = 300x + 50
-50 = 300x

-50/300 = x
-1/6 = x

In this exercise too we managed to arrive at a result and therefore the answer is rejected.

Let's move on to answer C:

y = 3

We will substitute:

0 = 3

We see that here an impossible result is obtained because 0 can never be equal to 3.

Therefore, we understand that the equation in answer C is the one that does not intersect the x-axis, and is in fact positive all the time.

Therefore answer D is also rejected, and only answer C is correct.

$y=3$

Choose the equation that represents a line with a negative domain of 0 < x .

$y=-2x$

Given the function is negative in the domain 4 > x

Find the equation of the line given that it passes through the point $(5,9)$

$y=9x-36$

Choose the equation that represents a straight line that is positive in the domain 8 > x

and passes through the point $(0,9)$.

$y=-1\frac{1}{8}x+9$

A line is negative in the domain

x < -2 .

Which equation represents the line?

All answers are correct.

Which function is positive in the domain below?

-7 > x

$y=-3x-21$

Given a function that is positive from the beginning of the axes. Plus the point (7,9) on the graph of the function. Find the equation for the function.

$y=1\frac{2}{7}x$

Choose the functions that fit the following description:

The function is positive in the domain 2 < x .

a. $y=3x+4$

b. $y=2x-4$

c. $y=-2x+4$

d. $y=2$

e. $y=4x-8$

f. $y=5x-14$

a, b, d, e

The following is a function that is positive in domain:

3 < x

Choose the equation that describes it given that the absolute value of the slope is 2.

$y=2x-6$

Given a function that is negative in the domain 4 < x only.

Moreover, its point of intersection with the y axis is $(0,-12)$

Find the equation daxis iscribing the line.

No solution