Can I have help writing an equation for
Line m has no y-intercept, and its x-intercept is (3, 0). Line n has no x-intercept, and its y-intercept is (0, -4).
I need to write one for line m and line n

Question

Can I have help writing an equation for 
Line m has no y-intercept, and its x-intercept is (3, 0). Line n has no x-intercept, and its y-intercept is (0, -4).
I need to write one for line m and line n

decarr432 · Answer

@mathmale

decarr432 · Answer

@roadjester

decarr432 · Answer

@DanJS

decarr432 · Answer

Would it be simply x=3?

decarr432 · Answer

I'm confused

tommynaut · Answer

Yes, you're right! Using that same logic you can work out line n too.

decarr432 · Answer

so simply y=-4 thanks

decarr432 · Answer

How so?

danjs · Answer

a line without one of the axis intercepts, will be parallel to that axis,

danjs · Answer

any form of slope at all will have all real values for x and y

tommynaut · Answer

That's right. This is an example of a question where the lines don't perfectly fit the model y = mx + b. Technically line n does, but in a strange way. We know m is the gradient of the line and b is the y intercept, so...

For line n, the y intercept is -4. As the line never crosses the x axis, it must be horizontal (m = 0). If m = 0, mx = 0x = 0. 
So
y = 0 - 4
y = -4

Line m is a bit more tricky. There is NO y intercept! Which means you don't have a "b" value at all! The "b" value isn't 0 (because that means the y intercept is 0, which is different from nothing).
So it's best to ignore y = mx + b for this one and just recognise that it's a vertical line.
If we think about it logically, x = 3 fits nicely as a description of the line because it's saying "for every point on the line, the x value is 3, regardless of the y value".

danjs · Answer

yeah, to make a line not cross y-axis, it will be  parallel to y axis (vertical)...
 and also pass through point (3,0),  so it has to be located at x=3

decarr432 · Answer

Yeah I'm using desmos graphing calculator and put x=3 and y=-4 and it gave me lines so idk what I should put

danjs · Answer

the equation x=3 or y=4 , can be shown as a single value point on the number line, but when you move to the plane, x=3 is now a line instead of a point
x=3 , and y has no restriction

danjs · Answer

x = 3,   all the points (3, y)

danjs · Answer

same thing for moving to 3 space,  - another dimension added

lines on the (x,y) plane , turn to planes on 3-space,   z has no restriction