2k+ 5k+1 + 10k+2 are three successive terms of a geometric sequence find the value(s) of k

Answer 1

I see 5 terms, not 3.

You will need brackets to identify the terms

Answer 2

Clearly, 10k+2 is 2(5k+1)
so, 5k+1 = 2(2k)
k = -1

The sequence is

-2 -4 -8 ...