As written
#color(white)("XXXX")#Since #x^2 = 9 rarr x=+-3#
#color(white)("XXXX")##color(white)("XXXX")#the Domain is #{-3,+3}#
#color(white)("XXXX")#and since #y=x#
#color(white)("XXXX")##color(white)("XXXX")#the Range is also #{-3,+3}#
Probable Intended equation: #y = x^2-9#
#color(white)("XXXX")#In this case the equation is defined for all Real values of #x#,
#color(white)("XXXX")##color(white)("XXXX")# so the Domain is #x epsilon RR#
#color(white)("XXXX")#the minimum value for #y# is #y=-9#,
#color(white)("XXXX")##color(white)("XXXX")#so the Range is #y epsilon [-9,+oo)#