21 they have too be right next to each other and threy have too be right
Answer:

Step-by-step explanation:
The complete question in the attached figure
we have

we know that
(ab)(x) is equal to the product of a(x) and b(x)
so

Applying distributive property



This is a quadratic equation
The other expressions not produce a quadratic equation
A. It is always true
B. -4*6=-24
3*-7=-21
C. Whenever you have a negative being multiplied by a positive the product is always negative