4m + 1, m + 1 and 10 - m are the first three terms of a geometric sequence. Find t4.

Answer 1

since the difference is constant,

(m+1)-(4m+1) = (10-m)-(m+1)
m = -9

so the sequence is

-35, -8, 19, 46, ...

Answer 2

But they are not geometric sequence..