Question

Please help me figure this one out!

Answer 1

7

Explanation:

∑ᵢ₌₁³ (4 × (½)ⁱ⁻¹)

This is the sum of the first 3 terms of the sequence.

The first 3 terms are:

4 × (½)¹⁻¹ = 4

4 × (½)²⁻¹ = 2

4 × (½)³⁻¹ = 1

So the sum is:

∑ᵢ₌₁³ (4 × (½)ⁱ⁻¹) = 4 + 2 + 1 = 7