Linear sequences nth term exam question

Question

The nth term of a sequence is 4n + 1 where n is a positive integer.

a) Find an expression for the sum of the (n-1)th and nth terms of this sequence.

Give your answer in simplest form.

What I did: 4n + 1 + (4n) = 8n + 1

b) The sum of two consecutive terms in the sequence is 70.

Work out the larger of the two terms.

8n + 1 = 70

8n = 69

Idk what to do for this question.

Thank You and help is appreciated.

Answer 1

You have done wrongly from the first question.

The $\left(n-1\right)$ term of the sequence is $4\left(n-1\right)+1=4n-3$. Therefore, the sum of the $n$th term and the $\left(n-1\right)$th term is $\left(4n+1\right)+\left(4n-3\right)=8n-2$

The second question is like that: $$8n-2=70 \\ 8n=72 \\ n=9$$ So the larger term is $4n+1=4*9+1=37$

Answer 2

${t}_n\;+\;{t}_{(n-1)} = (4n+1)+(4(n-1)+1)$ $\\$ i.e 8n - 2 = 70 hence n= 9 the number are 33 , 37