What do you do when an equation of a line has no "x" or when x and y are added together to a certain number

How do you determine the slope and the y-intercept in these equations:
1) y = -1
2) x + 2y = 4
3) 4x + 2y = 0

I'm stuck and I need some help... please!

1. y = -1 This is simply a straight line passing through the y axis a -1. Therefore the gradient is 0 as the line does not move up or down and the y intercept is (0,-1) as the graph passes through the y axis at -1.

2. x + 2y = 4 You need to rearrange this equation to get it in the form of y = ... to do this you do this..
2y = 4 - x
then you divide it by 2 to get the y by its self.
this leaves you with
y = 2 - 0.5x

The slope of this graph is -0.5 and the y intercept is at (0,2)

3. 4x + 2y = 0 Again you have to rearrange to get y = 0 - 2x
the slope is -2 and the y intercept (0,0)




If you don't understand how i worked out the slope or y intercept then you can simply work out two points.
If you have x = 0 you can put 0 in to the equation wherever you see x and solve the equation to work out what y equals. This will give you the y intercept :)

To work out the slope you can use this equation 'the change in y' divided by 'the change in x' this requires you to find two points on the graph and work out the difference between the y and x values, one you have done this you can put them in to the equation for slope and get your answer.


I hope this helps :)

Write the equation in the form y = ax + b, the the slope is a.

1) y = 0x - 1
The slope is 0

2) x + 2y = 4
2y = -x + 4
y = -1/2 x + 2
The slope is -1/2

3) 4x+2y = 0
2y = -4x
y = -2x
The slope is -2