Sa se determine progresia aritmetica ([tex]a_{n} [/tex]) n[tex] \geq [/tex]1 stiind ca:

[tex] a_{1} [/tex]+[tex] a_{2} [/tex]=8

[tex]S_{4} [/tex]=22


Răspuns :

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