5. Recursion and Iteration
Sign In
-4, -14, -34, -74, -154
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.