Answer:
Correct answer: t₇ - a₇ = 2 · 7⁶, t₂₀ - a₂₀ = 2 · 7¹⁹
Step-by-step explanation:
Given:
Geometric sequence 2, 14, 98, 686, ......
First term is a₁ = 2
Second term a₂ = 14
Third term a₃ = 98
The quotient ( ratio) is obtained as follows:
r = 14 / 2 = 98 / 14 = 7
r = 7
n-th term is obtained as follows:
aₙ = a₁ · rⁿ⁻¹
according to this:
a₇ = 2 · 7⁶ = 2 · 117,649 = 235,298
a₂₀ = 2 · 7¹⁹ = 2 · 11,398,895,185,373,143 = 22,797,790,370,746,286
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