∴x 1=4,x2=2

∫0A and 0B are the two roots of the equation, and 0A < 0B.

∴0A=2,0B=4

∴ A(0，2)，B(-4，0)

∫0A:AC = 2:5

∴ AC=5

∴OC=OA+AC=2+5=7

∴ C(0，7)

∠∠BAO =∠CAP，∠CPB=∠BOA=90O

∴∠PBD=∠OCD

∠∠BOA =∠COD = 90O

∴△BOA∽△COD

∴ BO\CO=OA\OD

∴ OD=(OA*CO)\BO=7\2

∴d( 7 \ 20)

Let the analytical formula of straight line CD be y = kx+b.

Let x = 0 and y = 7；; X=7\2 and y=0 are:

b=7

(7\2)k+b=0

b=7

k =-2

∴yCD=-2x+7

(3) Existence, P1(-5.5,3), P2 (9.5,3), P3 (-2.5,3)