Question

Three #s, a,b, and c, form an arithmetic sequence. Increasing a by 1 or c by 2 results in a geometric sequence. Find b, with an explanation please!

Answer 1

a = a
b = a+d
c = a + 2d
Geometric:
a+1
b
c+2

(a+1)(c+2) = b^2
substitute b = a+d and c = a+2d in to this equation

Answer 2

thank you! explained it better than my teacher

Answer 3

actually it says "or" so you should get
(a+1)(c) = b^2
and
(a)(c+2) = b^2
so you can solve for both "a" and "d"