Answer:
C. 9
Step-by-step explanation:
y = -4x^2 + 2kx
subtitute 3:
y = -4(9)^2 + 2k(9)
y = -4(81) + 18k
let y = 0
=> 0 = -324 + 18k
=> k = 324/18 = 9
this is my calculations hope it helps
