Can you solve these?

What is the missing constant term in the perfect square that starts with x^2 -20x

The constant of proportionality is always the where k is the constant of proportionality. additionally, you can find the constant of proportionality by finding the ratio for any point onasap

If set d is not the empty set but is a subset of set e, then which of the following is true? d ∩ e = d d ∩ e = e d ∩ e = ∅