Answer:
2, 0.5 and 0.25.
Step-by-step explanation:
The nth term an = a1r^(n-1) where a1 = first term and r = the common ratio.
The sum to infinity = a1/(1-r) for -1 < r < 1.
So we have:
Second term a2 = 1 = a1(r)(2-1) = a1r and
4 = a1/(1 - r)
From the first equation:
a1 =1/r
So substituting in the second equation:
4 = 1/ r / (1 - r)
4 = 1 / r - r^2
4r - 4r^2 = 1
4r^2 - 4r + 1 = 0
(2r - 1)(2r - 1) = 0
r = 0.5
So the first term a1 = 1/ r =1/0.5 = 2.
The third = 1*0.5 = 0.5
and the 4th = 0.5*0.5 = 0.25.
