P2 is easy - P1(3) already provides the two quadratic factors for the expression in P2. so just solve the two quadratic expressions n u will get the 4 roots for P2.
same thing for P3...the cubic expression is equal to (x+1)(x^2 - 2x + 5). solve the quadratic eqn. those 2 roots plus -1 are the solutions for P3.
refer to ans of ur previous Q, the procedure is exactly the same :)