Question

URGENTEEE!!

Quantos termos tem a PG (1,3,9...,729)?

Answer 1

an = a1 . q^n-1
729 = 1 . 3 ^n-1
3^n-1 = 729
3^n-1 = 3^6
n-1 = 6
n = 6+1
n= 7

Answer 2

An = 729

a₁ = 1

q = a₂ / a₁

q = 3/1

q = 3

n = ?

An = a₁ * qⁿ⁻¹

729 = 1 * 3ⁿ⁻¹

3ⁿ⁻¹ = 729 / 1

3ⁿ⁻¹ = 729

3ⁿ⁻¹ = 3⁶

n - 1 = 6

n = 1 + 6  

n = 7