Imagine that we have a solid line
(-1,0) and (0, 1) are on the line
Slope = (1-0) /( 0 - - 1) = 1/1 = 1
Equation if this were a solid line would be (using ( 0.1) )
y = -x + 1
However ....we have a dashed line so the equation is either
y < -x + 1 or y > x + 1
Note that (0,2) is in the yelllow region and this satisfies the 2nd inequality
So....we have
y > x + 1 rearrange as
x + 1 < y and again
x - y + 1 < 0 or x - y < - 1
(Either form is correct )
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