Question 547550
You can solve for y and get {{{y=(3/8)x+7/8}}} which assigns just one y value to each x value, so it is a function.
The relation {{{x^2+y^2=1}}}is not a function because for {{{x=0}}} there are two values for y: {{{y=1}}} and {{{y=-1}}}.
Another way of checking is looking at a graph and seeing if a vertical line could intersect the graph more than once.
The graph of {{{ 8y = 7 + 3x}}} is a slanted line, so it's a function.
The graph of {{{x^2+y^2=1}}}is a circle, so you know it's not a function because a vertical line can cross the circle at two points.