Question

o capital de r$2.000,00,aplicado a juros compostos,rendeu,apos 4 meses,juros de r$165,00.qual foi a taxa de juros mensal ?

Answer 1

C = 2000,00
J = 165,00
M = C + J
M = 2000 + 165 = 2165
n = 4 meses
i = ?
M = C . ( 1 + i )ⁿ
2165 = 2000 . ( 1 + i )⁴
2165/2000  = ( 1 + i )⁴
1,0825 = ( 1 + i )⁴
⁴√1,0825 = 1 - i
1,0200 = 1 - i
1,0200 - 1 = i 
 i = 0,0200 x 100
i = 2%

Answer 2

C → 2000

t → 4 meses

J → 165

i → ???

M → ?

_____________

M=C+J

M=2000+165

M=R$2.165,00

_____________

M=c·(i+1)^t

2165=2000·(i+1)⁴

2165/2000=(i+1)⁴

1.0825=(i+1)⁴

i+1=⁴√1.0825

i+1=1,02 (considerando duas casas decimais)

i=1,02-1

i=0,02

i=0,02×100%

i=2%a.m