Posted by Sam on .
How do I find the set of all points of y=8 on a graph?

Math/209 
Reiny,
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), ... 
typo  Math/209 
Reiny,
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. 
Math/209 
Sam,
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?

Math/209 
Reiny,
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"