Math/209
posted by Sam on .
How do I find the set of all points of y=8 on a graph?

Any equation in x and y merely gives you a description of the relationship between the x and y coordinates of the points in a relation.
e.g.
x=y = 6 means that as long as the x and the y of a given point add up to 6, that point belongs.
So in your case it says that y = 8 , with no mention of x.
That means that we don't put any restriction on x and x can be anything we want it to be
as long as our y is 8, anything goes
so some points:,
(1,8), (5,8), (3,8), (3.56,8), (√2,8), (0,8), ... 
4th line should have been
x+y = 6 means that as long as the x and the y of a given point add up to 6, that point belongs.
but you probably guessed that anyway. 
Can you please explain to me how you find the points, such as (1,8) and (3,8)are mulitilying, adding, what exactly do I have to do to get this?

As I stated, since there is no x in your equation, x can be any value you want it to be, as long as the y value is 8.
so I just made up any x I could think of.
There is no mathematical operation involved at all, since all it said that y = 8 or
"the y value has to be 8"