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 4 Page 695

The given formula means that, after the first term of the sequence, every term a_(n+1) is 6 less than the previous term a_n multiplied by 2.

-4, -14, -34, -74, -154

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

a_1&=-4 a_(n+1)&=2a_n-6 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)=2a_n-6 2a_n-6 a_(n+1)
- a_1= -4 - -
1 a_(1+1)=2a_1-6
⇕
a_2=2a_1-6
a_2=2 a_1-6
⇓
a_2=2( -4)-6
a_2= -14
2 a_(2+1)=2a_2-6
⇕
a_3=2a_2-6
a_3=2 a_2-6
⇓
a_3=2( -14)-6
a_3= -34
3 a_(3+1)=2a_3-6
⇕
a_4=2a_3-6
a_4=2 a_3-6
⇓
a_4=2( -34)-6
a_4= -74
4 a_(4+1)=2a_4-6
⇕
a_5=2a_4-6
a_5=2 a_4-6
⇓
a_5=2( -74)-6
a_5= -154

The first five terms of the sequence are -4, -14, -34, -74, and -154.