Question

I need help with the two I have gotten wrong.

Answer 1

It is given that:

`a_1=5,a_2=15`

The common ratio r is calculated by the formula:

`r=(a_n)/(a_(n-1))=(a_2)/(a_1)=(15)/(5)=3`

Hence r=3.

The given formula is:

`\begin{gathered} a_n=a_1r^(n-1) \\ a_(10)=a_1(r^(10-1))=a_1r^9 \end{gathered}`

Substitute the calculated values to get:

`a_(10)=5(3)^9=98415`

Hence the tenth term is 98415