Question

calcule a soma dos termos da pg ( 4, 16 , ...
16384 )

Answer 1

a1 = 4
a2= 16
q = 16/4 = 4 ****
an = 16384

16384 = 4 * 4ⁿ⁻¹
4ⁿ⁻¹ = 16384/4 = 4096
( 2²)ⁿ⁻¹ = 2¹²
( 2)²ⁿ⁻² = 2¹²
2n - 2 = 12
2n = 12 + 2
2n = 14
n = 7 *****

S7 =  4 ( 4⁷  - 1 )/ ( 4 - 1)
S7 = 4 * ( 16384 - 1)/3
S7 = 4 *( 16383)/3 
S7 = 4 * 5461 =21844 ****