Question

Clasa a 9-a exercitiul 7

Answer 1

2=2+0
10=2+8*1
18=2+8*2
..........
162=2=8*20
in totalde la 0 la 20, avem21 de numerre
5=5+0
12=5+7*1
19=5+7*2
..............
1048=5+7*149
de la 0 la 149 avem 150 numere

Answer 2

a)$2,10,18,...,162$
$a_2=a_1+r$
$r=a_2-a_1$
$r=10-2$
$r=8$
$a_n=a_1+(n-1)r$
$162=2+(n-1)*8$
$162=2+8n-8$
$168=8n$
$n=\frac{168}{8}$
$n=21$
b)
$5,12,19,...,1048$
$a_2=a_1+r$
$r=a_2-a_1$
$r=12-5$
$r=7$
$a_n=a_1+(n-1)r$
$1048=5+(n-1)*7$
$1048=5+7n-7$
$1050=7n$
$n=\frac{1050}{7}$
$n=150$