Question 899892
A function is a special type of relation. 
 If for {{{any}}} value that is the{{{ first}}} in an ordered 
 pair, there is {{{only}}} one value that is the ({{{x}}}) {{{second}}} 
 value ({{{y}}})  in any of the ordered pairs, then the 
 relation is a FUNCTION. Or, a function is only if for every {{{x}}} there is only ONE {{{y }}}. But  if {{{2}}} different {{{x}}} values have the same {{{y}}} value, it's still a {{{function}}}.


 you have {({{{1}}}, {{{-9}}}), ({{{3}}}, {{{7}}}), ({{{4}}}, {{{-2}}}), ({{{8}}}, {{{-2}}}), ({{{11}}}, {{{4}}})}

since in pairs ({{{4}}}, {{{-2}}}) and ({{{8}}}, {{{-2}}}), values {{{x=4}}} and {{{x=8}}} have same value {{{y=-2}}}, it {{{IS}}} a FUNCTION because if {{{2}}} different {{{x}}} values have the same {{{y}}} value, it's still a {{{function}}}