Question 82200
how do I know whether a relation is a function or not? 
A relation is a function if for each value x takes there is only one y value.
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and how am I supposed to graph this type of equation?   my work sheet says to "graph each equation by plotting ordered pairs" and then it gives me several equations such as this one:
 y = 2x - 1
To graph it you need two points:
If x=0, y=2*0-1 = -1 giving you point (0,-1)
If x=1, y=2*1-1 = 1 giving you point (1,1)
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Plot these two points; draw a line thru them; that is your graph.
{{{graph(400,300,-10,10,-10,10,2x-1)}}}
Cheers,
Stan H.