You're browsing Puzzling.SE when suddenly you uncover a massive conspiracy. The posters of the "Security to the Party" questions are just posting 7 or 8 random numbers and then accepting the second or third answer which explains the data.
Infuriated, you attempt to break into the Dark Puzzlers Chat. However, there is a guard, et cetera.
A puzzler arrives. The guard says
1 5 2 1 4 3 8, and she replies
10 2 6.
A second puzzler appears. The guard says
CODREEF, and he replies
A third puzzler arrives. The guard says
1.3 2.0 1.6 1.8 2.2 2.3 2.4, and the puzzler replies
2.0 2.6 2.6.
For the fourth puzzler, the guard says
6, 3x^2+1, 6x+8, 6(x+6)^2, (x+1)(3x+5), sin(x)/x, (x+1)^2(x+2). The puzzler complains that the last one is impossible and leaves in a huff.
Obviously, you've heard enough, because anyone can work out any pattern after four examples. You approach the guard.
The guard says
Bleach as needed, Doctor Whooves's cutie mark, Play video, Infinity, Give way to traffic, Cancer horoscope, Normal subgroup. What should you reply?