Question 656751
{{{y^2=7x}}}.....=>.......{{{y=sqrt(7x)}}}..=>....±{{{sqrt(7x)}}}

It does not provide a {{{unique}}} {{{y}}} value for each {{{x}}} value because,
±{{{sqrt(7x)}}}

so, {{{y}}} is {{{not}}} a function of {{{x}}}  in {{{y^2=7x}}}