Answer:
a) c=64
b)c=100
c)c=324
d)c=1
Explanation:
I am assuming that you want c to be a value that makes the quadratic factorable.
In order for it to be factorable, you need to find the perfect square trinomial: you divide the b value by 2, and then square it.
a) -16/2=-8, -8^2=64
b) -20/2=-10, -10^2=100
c)36/2=18, 18^2=324
d)2/2/1, 1^2=1