Question

A store has a sale on books. The price is $17.55 for one book, $16.70 each for 2 books, $15.85 each for 3 books, and $15 each for 4 books. If this pattern continues, how much per book will it cost to buy 7 books

Answer 1

1 book is 17.55
2 books is 16.70
3 books is 15.85
4 books is 15
5 books is 4.15
6 books is 4.30
7 books is (3.55)

Answer 2

The cost for each book will be $\boxed{\ 12.45}$ if the person buy 7 books.

Further explanation:

The arithmetic sequence can be expressed as follows,

${a_1}, {a_2}, {a_3}$......

Here,$a{\text{ or }}{a_1}$ represents the first term, ${a_2}$ represents the second term, and so on.

The common difference “d” can be obtained as follows,

$\boxed{d = {a_2} - {a_1}}$

The nth term can be obtained as follows,

$\boxed{{a_n} = a + \left( {n - 1} \right)d}$

Explanation:

The cost of a book is $\ 17.55.$

The cost of a book is $\ 16.70$ if the person buys 2 books.

The cost of a book is  $\ 15.85$ if the person buys 3 books.

The cost of a book is $\ 15.00$ if the person buys 4 books.

The sequence is $\ 17.55, \ 16.70, \ 15.85, \ 15.00.$

The first term is $\ 17.55,$ the second term is $\ 16.70.$

The common difference “d” can be obtained as follows,

$\begin{aligned}d&={a_2} - {a_1}\\&=16.70 - 17.55\\&=- 0.85\\\end{aligned}$

The cost for each book if the person buys 7 books can be obtained as follows,

$\begin{aligned}{a_6}&= 17.55 + \left( {7 - 1} \right)\left( { - 0.85} \right)\\&= 17.55 + 6\left({ - 0.85} \right)\\&= 17.55 - 5.1\\&=\ 12.45\\\end{aligned}$

The cost for each book will be $\boxed{\ 12.45}$ if the person buy 7 books.

Learn more:

1. Learn more about inverse of the functionhttps://brainly.com/question/1632445.

2. Learn more about equation of circle brainly.com/question/1506955.

3. Learn more about range and domain of the function https://brainly.com/question/3412497

Answer details:

Grade: Middle School

Subject: Mathematics

Chapter: Arithmetic Sequence

Keywords: Store, books, price, $17.55, 2 books, 3 books each cost $16.40, pattern continues, cost, 7 books.