a)
[tex]a_{22} = - 92 \: \: \: r = - 3[/tex]
[tex] - 92 = a_{1} + (22 - 1) \times ( - 3) \\ - 92 = a_{1} + 21 \times ( - 3) \\ - 92 = a_{1} - 63 \\ - 92 + 63 = a_{1} \\ a_{1} = - 29[/tex]
b)
[tex]a_{7} = 37 \: \: \: \: \: r = 5.5[/tex]
[tex]37 = a_{1} + (7 - 1) \times 5.5 \\ 37 =a_{1} + 6 \times 5.5 \\ 37 = a_{1} + 33 \\ a_{1} = 37 - 33 \\ a_{1} = 4[/tex]
