Question

I need the correct answer to the 4 I have gotten wrong please.

Answer 1

Given:

`\begin{gathered} t_n=t_(n-1)+7 \\ First\text{ term, }t_1=-5 \end{gathered}`

Hence we can write,

`d=t_n-t_(n-1)=7`

Here, d is the common difference.

Now, the n th term formula can be written as,

`t_n=t_1+(n-1)d`

So, the term t4 can be found as,

`\begin{gathered} t_4=-5+(4-1)7 \\ =-5+3*7 \\ =-5+21 \\ =16 \end{gathered}`

Now, the term t20 can be found as,

`\begin{gathered} t_(20)=-5+(20-1)7 \\ =128 \end{gathered}`

So, the answers can be written as,

`\begin{gathered} t_4=(-5)+(3)(7) \\ t_4=16 \end{gathered}`
`\begin{gathered} t_(20)=(-5)+(19)(7) \\ t_(20)=128 \end{gathered}`