Answer:
42 + 2/3
Explanation:
First, to calculate the sum of an infinite geometric series, our formula is
a₁/(1-r), with a₁ being the first term of the series and r being the common ratio. Therefore, we want to find both a₁ and r.
To find r, we can first determine that 2 * r = a₄ and a₄ * r = a₅, as the ratio separates one number from the next in a geometric series. Therefore, we have
2 * r * r = a₅
2 * r² = 1/8
divide both sides by 2 to isolate the r²
r² = 1/16
square root both sides to isolate r
r =± 1/4. Note the ± because r²=1/16 regardless of whether r = 1/4 or -1/4. However, because all terms are positive, r must be positive as well, or a₄, for example, would be 2 * (-1/4) = -0.5
Therefore, r = 1/4 .
To find the first term, we know that a₁ * r = a₂, and a₂ * r = a₃. Therefore, a₁ * r² = a₃ = 2
a₁ * 1/16 = 2
divide both sides by 1/16 to isolate a₁
a₁ = 2 * 1/ (1/16)
= 2 * 16
= 32
Plugging a₁ and r into our infinite geometric series formula, we have
a₁/(1-r)
= 32 / (1-1/4)
= 32/ (3/4)
= 32/ 0.75
= 42 + 2/3