Zad. 5
[tex]a_3 = 5\\a_6 = 11\\\\a_n = a_1+(n-1)*r\\\\\left \{ {{5=a_1+2r} \atop {11=a_1+5r}} \right. \\\left \{ {{-5=-a_1-2r} \atop {11=a_1+5r}} \right. \\6=3r\\r = 2\\5=a_1+2*2\\5=a_1+4\\1=a_1\\a_2=1+2\\a_2=3[/tex]
Odp. D
