Need help with a question on functions (1 Viewer)

[Snowcub17]

the question is Y> 2x -1 and it says does this define a function. i put a table of values from -4-4 and got answers and then plotted and it only touches the graph once so i put yes but the book has no, can someone help me please?

 

[nrlwinner]

the question is Y> 2x -1 and it says does this define a function. i put a table of values from -4-4 and got answers and then plotted and it only touches the graph once so i put yes but the book has no, can someone help me please?

Well a function is defined as an equation with 1 y-value for each x-value. In this case, if the equation was y=2x-1, then yes it would be a function. However, this equation is a region, meaning that there would be more than 1 y-value for each x-value.

First thing you do is you draw the graph and shade in the region. In this case, the region would be to the left of the line. Take the x-value of 0. There would not only be a y-value of 0, but also 1,2,3,4,etc.

4 > 0-1
3 > 0-1
0 > 0-1

That's why the equation is a relation and not a function. Hope this helps. If you need any more help, reply back or PM me.