Respostas

2014-07-08T08:30:40-03:00
Numero 5
a_{n} = a_{1}+ (n-1)r
a_{23} = a_{1}+ (23-1)r
a_{23} =50
 a_{1}= 3r
50= 3r+ (23-1)r
50 = 3r+22r  \\ 50=25r
r=2

Numero 6
a_{n} = a_{1}+ (n-1)r
a_{10} = a_{1}+ (10-1)r
a_{10} =65
 a_{1}= 2
a_{10} = 2+ 9r
65 = 2+ 9r
63 = 9r
 \frac{63}{9} =r
r=7
a_{n} = 2+ 7(n-1)

Numero 7
a_{n} = a_{1}+ (n-1)r
a_{n} =-48
 a_{1}= 8
-48 = 8+ (n-1)(-4)
-48 = 8-4n +4
-48-12 = -4n
 \frac{-60}{-4}=n \\ n=15
2 5 2
obrigada :D mas e a 7?
Tá aí :D
Tá certinho?
eu acho q sim ;)