Question 1103781
<pre>
{{{3x-y^2=9}}}

is not a function because (6,-3) and (6,3) both satisfy
{{{3x-y^2=9}}} and a function cannot have two different
y-values for the same x-value.

{{{3(6)-(-3)^2=9}}}
{{{18-9=9}}}
{{{9=9}}}

Also

{{{3(6)-(3)^2=9}}}
{{{18-9=9}}}
{{{9=9}}}

----

{{{3x - y = 9}}}
{{{-y=-3x+9}}}
{{{y=3x-9}}}
Thus for each value of x, there is only one value of y,
since 3x-9 has but one value.

Therefore this is a function

----

{{{3x^2-y^2=9}}}

is not a function because (&#8730;6,-3) and (&#8730;6,3) both satisfy
{{{3x^2-y^2=9}}} and a function cannot have two different
y-values for the same x-value.

{{{3(sqrt(6))^2-(-3)^2=9}}}
{{{3(6)-9=9}}}
{{{18-9=9}}}
{{{9=9}}}

Also

{{{3(sqrt(6))^2-(3)^2=9}}}
{{{3(6)-9=9}}}
{{{3(6)-(3)^2=9}}}
{{{18-9=9}}}
{{{9=9}}}

Edwin</pre>