McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
5. Recursion and Iteration
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Exercise 3 Page 695

The given formula means that, after the first term of the sequence, every term a_(n+1) is the sum of 2 and the previous term a_n multiplied by 3.

5, 17, 53, 161, 485

Practice makes perfect
We are asked to write the first five terms of a sequence, given a recursive formula.

a_1&=5 a_(n+1)&=3a_n+2 To do so, we will use a table. To find a_2 we will substitute 1 for n in the above formula. To find a_3 we will substitute 2 for n, and so on.

n a_(n+1)=3a_n+2 3a_n+2 a_(n+1)
- a_1= 5 - -
1 a_(1+1)=3a_1+2
⇕
a_2=3a_1+2
a_2=3 a_1+2
⇓
a_2=3( 5)+2
a_2= 17
2 a_(2+1)=3a_2+2
⇕
a_3=3a_2+2
a_3=3 a_2+2
⇓
a_3=3( 17)+2
a_3= 53
3 a_(3+1)=3a_3+2
⇕
a_4=3a_3+2
a_4=3 a_3+2
⇓
a_4=3( 53)+2
a_4= 161
4 a_(4+1)=3a_4+2
⇕
a_5=3a_4+2
a_5=3 a_4+2
⇓
a_5=3( 161)+2
a_5= 485

The first five terms of the sequence are 5, 17, 53, 161, and 485.