Lineman Aptitude Test Question: Find z if the line (z-3)y + (z+5)x = 8 is parallel to axis x.

[tnotrika]

I'm unsure of how to answer the following question. The question states: Find z if the line (z-3)y + (z+5)x = 8 is parallel to axis x.

Answer choices: -5, -3, 3, 5, 8

 

[BigBeachBanana]

Write the line in the slope-intercept form: [imath]y=mx+b[/imath].

What do you know about the slopes of parallel lines?

 

[Steven G]

If a line is parallel to the x-axis is in in the form of
1) x= some constant
or 2) y = some constant?

This is strike number 2 where you submitted posts with showing no work.
Try reading the forum's posting guidelines

 

[tnotrika]

Write the line in the slope-intercept form: [imath]y=mx+b[/imath].

What do you know about the slopes of parallel lines?

so if I write it in slope-intercept form I get y = -(z+5)x/(z-3) + 8/(z-3) right? and the slopes of parallel lines are the same aren't they?

 

[tnotrika]

If a line is parallel to the x-axis is in in the form of
1) x= some constant
or 2) y = some constant?

This is strike number 2 where you submitted posts with showing no work.
Try reading the forum's posting guidelines

I'm sorry for posting with no work I'm a tutor who's trying to understand how this problem goes to better understand how to help my student.

 

[BigBeachBanana]

so if I write it in slope-intercept form I get y = -(z+5)x/(z-3) + 8/(z-3) right?

Yes, the form is correct.

so if I write it in slope-intercept form I get y = -(z+5)x/(z-3) + 8/(z-3) right? and the slopes of parallel lines are the same aren't they?

Yes, to the second question. If the line is parallel to the x-axis i.e. the line [imath]y=0[/imath]. What is the slope?
Equate the slopes and solve for [imath]z[/imath].

 

[Steven G]

A line parallel to the x-axis is ALWAYS in the form of y=b. That is, there is no x in the equation.

If you have Ay + Bx = C and this line is parallel to the x axis, then Ay = C or y =C/A. That is, B=0.
Think about it, a horizontal line has a slope of 0!