T and N 17

I know the method but not the answer!

1. Find equation of the tgt at P:-
You know P and u know the slope of tgt at P. So find equation of tgt.

2. Find pt of intersection :-
Find where the tgt meets the curve again by solving the two equations. Get Q.

3. Get the mid point of PQ and hope for the best :-
Mid point of PQ will hopefully be (x,1-9x+28x²-28x³)!!!!!!!!

please somebody solve it completely!!!!!!!!!!!!!

Done.. !!!

I should get a treat for this :)