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Pearson Algebra 1 Common Core, 2011

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Pearson Algebra 1 Common Core, 2011 View details

7. Arithmetic Sequences

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Exercise 46 Page 279

Substitute 2, 4, and 11 for n in the given explicit formula.

2, -4, - 25

Practice makes perfect

We want to find certain terms of an arithmetic sequence described by its explicit formula. A(n)=5+(n-1)(-3)For the given explicit formula, we can find the second, fourth, and eleventh terms of the sequence by substituting 2, 4, and 11 into the formula for n. Let's start with the second term.

A(n)=5+(n-1)(-3)

n= 2

A( 2)=5+( 2-1)(-3)

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Evaluate right-hand side

Subtract term

A(2)=5+(1) (-3)

Identity Property of Multiplication

A(2)=5+(-3)

a+(- b)=a-b

A(2)=5-3

Subtract term

A(2)=2

Now, let's do the same thing for the fourth and eleventh terms.

A(n)=5+(n-1)(-3)
Term	Substitute	Simplify
2	5+( 2-1)(- 3)	2
4	5+( 4-1)(- 3)	- 4
11	5+( 11-1)(- 3)	- 25

The second, fourth, and eleventh terms are 2, - 4, and - 25, respectively.

Subchapter links

Lesson Check p.278

Practice and Problem-Solving Exercises p.279-281

Standardized Test Prep p.281

Mixed Review p.281