Question

Find the AP whose nth term is 9 - 5n.

Answer 1

$$\begin{gathered} \mathrm{The}{\mathrm{n}}^{\mathrm{th}}\mathrm{term}\mathrm{of}\mathrm{the}\mathrm{given}\mathrm{AP}\mathrm{is}, \\ {\mathrm{a}}_{\mathrm{n}}=9-5\mathrm{n} \\ \mathrm{Put}\mathrm{n}=1,\mathrm{we}\mathrm{get}{\mathrm{a}}_1=9-5\times 1=9-5=4 \\ \mathrm{Put}\mathrm{n}=2,\mathrm{we}\mathrm{get}{\mathrm{a}}_2=9-5\times 2=9-10=-1 \\ \mathrm{Put}\mathrm{n}=3,\mathrm{we}\mathrm{get}{\mathrm{a}}_3=9-5\times 3=9-15=-6 \\ \mathrm{Put}\mathrm{n}=4,\mathrm{we}\mathrm{get}{\mathrm{a}}_4=9-5\times 4=9-20=-11 \\ \mathrm{So},\mathrm{required}\mathrm{AP}\mathrm{is}, \\ 4,-1,-6,-11,............ \end{gathered}$$