Plz Help! Equations?

Question

x²-px+9=0

a)write down the sum of roots and product of roots;

b)find p if twice the sum of roots equals the product;

c)find p if the roots are unequal.

This question is in regards to quadratic equations with the formula -b±sqrt(b²-4ac) ÷ 2a

Answer 1

Sum of roots = -b/a =p
product of roots = c/a = 9

2p = 9 --> p =4.5

p^2>4ac --> p^2 >4*9 --> p>6

Answer 2

sum of roots is p (-p is the opposite of the sum)

product of roots is 9

(b) 2p=9 means p=9/2.

(c) If p=6 or p=-6 then the roots are EQUAL, if p is anything else then they are unequal.

Answer 3

sum of roots is p and product is -9

x+y=p xy=9
so 2(x+u) = 2p
and 2p=9
p = 9/2

not sure about the third