Question

Sa se determine progresia aritmetica ($a_{n}$) n$\geq$1 stiind ca:

$a_{1}$+$a_{2}$=8

$S_{4}$=22

Answer 1

a1+a1+r=8
2a1+r=8
s4=22 rezulta( a1+a1+3r)*4=44
2a1+3r=11
r=8-2a1
2a1+3(8-2a1)=11
2a1+24-6a1=11
13=4a1 a1=4/13
 a1+a1+r+a1+2r+a1+3r=22
4a1+6r=22
2a1+3r=11