If f(x) = 12 - x^2/2 and f(2k) = 5k, what is…

If f(x) = 12 - x^2/2 and f(2k) = 5k, what is one possible value for k?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #4023