We know that if f(a)=b then 
and
if
then f(b)=a
so
since
therefor, f(-2)=0
we have 2 points, (-2,0) and (0,3)
we can use slope intercept form
y=mx+b
m=slope
b=y intercept
we have when x=0, y=3, that is the y intercept
y=mx+3
substitute the other point
(-2,0)
x=-2, y=0
0=-2m+3
-3=-2m
divide both sides by -2
the equation is
or
3x-2y=-6 in standard form
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and
if
so
since
we have 2 points, (-2,0) and (0,3)
we can use slope intercept form
y=mx+b
m=slope
b=y intercept
we have when x=0, y=3, that is the y intercept
y=mx+3
substitute the other point
(-2,0)
x=-2, y=0
0=-2m+3
-3=-2m
divide both sides by -2
the equation is
or
3x-2y=-6 in standard form
<span />