Equation– y=10-3x
How many different ordered pairs (x,y) of positive integers satisfy the equation above?
A- none
B-1
C-2
D-3
E-5
Thanks!

A pretty good, low-impact way to go here is to use the TABLE function on your graphing calculator.

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Barring that, though, you can also get this one by plugging in small positive integer values for x and seeing what happens with y. When x = 1, y = 7. That works. When x = 2, y = 4. That works. When x = 3, y = 1. That works. When x = 4, y = –2. That doesn’t work. Because this is a linear equation and the graph won’t change directions, we know that no other ordered pairs will work.

 

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