Answer:
the other answer is zero.
Step-by-step explanation:
Step 1: Use the vertex form, [tex]y=a(x-h)^2+k[/tex], to determine the values of a, h, and k. The "k" value is always the "y" value in a ordered pair. Since there is no "k" value, the "k" value will just be zero. In turn, since the "k" value is zero... so will the "y" value be zero.
[tex]a=8\\\\h=21\\\\k=0[/tex]
