The sum of the first 6 terms of a geometric series is 15,624 and the common ratio is 5 what is the first term of the serious?

first term = 4

Step-by-step explanation:

Sₙ = (a₁ * (1 - rⁿ)) / (1 - r) a₁: first term r: common ratio n: terms

15624 = (a₁ * (1 - 5⁶)) / (1 - 5)

= (a₁ * - 15624) / - 4

a₁ x (-15624) = 15624 x (-4)

a₁ = 4

check: 4+20+100+500+2500+12500 = 15624