Given :
Set of x-intercepts {-3,1,7},
point through which it passes (-2,54)
Now,
Step 1: Substitute value of x intercepts in equation,
, we get,

... equation (1)
Step 2: substitute x an y with the point through which it passes,


∴ 
Step 3: Now, substituting value of a in equation (1), we have

(Requited cubic equation)