[tex] \div\: a_{1},a_{2},a_{3},6,a_{5},16[/tex]
[tex] = > a_{5}= \frac{6 + 16}{2} = \frac{22}{2} = 11[/tex]
[tex]a_{5} + r = 16[/tex]
[tex]11 + r = 16[/tex]
[tex]r = 16 - 11[/tex]
[tex]r = 5[/tex]
[tex]a_{3} + r = 6[/tex]
[tex]a_{3} + 5 = 6[/tex]
[tex]a_{3} = 6 - 5[/tex]
[tex]a_{3} = 1[/tex]
[tex]a_{2} + r = a_{3}[/tex]
[tex]a_{2} + 5 = 1[/tex]
[tex]a_{2} = 1 - 5[/tex]
[tex]a_{2} = - 4[/tex]
[tex]a_{1} + r = a_{2}[/tex]
[tex]a_{1} + 5 = - 4[/tex]
[tex]a_{1} = - 4 - 5[/tex]
[tex]a_{1} = - 9[/tex]
