Answer:
k=64
Step-by-step explanation:
(y-x)(y-x) = y^2-16y+k
Since the k is a "+," and two negatives (hence the negative middle value) multiply to make a positive, and since 16 has to be equal to 2x, we know that x is 8. Therefore, our equation is (y-8)(y-8), which is equal to y^2-16y+64.
