Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
Maintaining Mathematical Proficiency
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Exercise 3 Page 63

What is the first term of the sequence? What is the common difference between terms? Use these values in the explicit equation for arithmetic sequences.

Equation: a_n=0.6n+2.2
Value of a_(50): 32.2

Practice makes perfect
Explicit equations for arithmetic sequences follow a specific format. a_n= a_1+( n-1) d In this form, a_1 is the first term in a given sequence, d is the common difference from one term to the next, and a_n is the nth term in the sequence. For this exercise, the first term is a_1= 2.8. Let's observe the other terms to determine the common difference d. 2.8+0.6 →3.4+0.6 →4.0+0.6 →4.6... By substituting these two values into the explicit equation and simplifying, we can find the formula for this sequence.
a_n=a_1+(n-1)d
a_n= 2.8+(n-1)( 0.6)
a_n=2.8+0.6n-0.6
a_n=0.6n+2.2
This equation can be used to find any term in the given sequence. To find a_(50), the 50th term in the sequence, we substitute 50 for n.
a_n=0.6n+2.2
a_(50)=0.6( 50)+2.2
a_(50)=30+2.2
a_(50)=32.2
The 50th term in the sequence is 32.2.