[tex] \huge \bf༆ Answer ༄ [/tex]
We have to find : f (a - b) = ?
[tex]{ \qquad{ \sf{ \dashrightarrow}}} \: \: \sf \:f(x) = {x}^{2} - 3[/tex]
[tex]{ \qquad{ \sf{ \dashrightarrow}}} \: \: \sf \:f(a - b) = (a - b) {}^{2} - 3[/tex]
[tex]{ \qquad{ \sf{ \dashrightarrow}}} \: \: \sf \:f(a - b) = {a}^{2} + {b}^{2} - 2ab - 3[/tex]