Think about this ... x can be any value and y will always equal 3.5.
If x is 0, then y = 3.5
If x is 1, then y = 3.5
If x is 5, then y = 3.5
If x is -4, then y = 3.5
If x is -10, then y = 3.5
If you plot all these points on a graph you should begin to see that the graph is a horizontal line that intercepts the y-axis at +3.5 and continues on forever in both plus and minus directions.
Any time that there is no x term in the equation, the graph is a horizontal line that crosses the y-axis at the given value of y. For example, the graph of y= -4 would be a horizontal line that crosses the y-axis at the point -4 and continues on forever in both directions (to the left and to the right).
