## anonymous one year ago Which of the following recursive formulas represent the same arithmetic sequence as the explicit formula an=5+(n-1)2?

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1. anonymous

where r the options?

2. amoodarya

to find choice find $a_n-a_{n-1}$

3. anonymous

(An-1+5)•2 An=an-1•5 An=an-1+5 An=an-1+2

4. welshfella

the common difference is 2 each term is obtained from the last by adding 2

5. welshfella

which of the options will fit that?

6. anonymous

a?

7. amoodarya

$a_n=5+2(n-1)\\a_{n-1}=5+2((n-1)-1)=5+2(n-2)\\a_n-a_{n-1}=\left[ 5+2(n-1) \right]-\left[ 5+2(n-2) \right]=\\5-5+2(n-1-(n-2))\\a_n-a_{n-1}=2$

8. welshfella

no not a

9. anonymous

Oh! I thinks it's b!

10. welshfella

i think you are guessing the first term is 5 and the second is 7 put an = 7 and an-1 = 5 and see which of the options fit

11. anonymous

An-1=5

12. welshfella

try option b An = 7 An-1 * 5 = 5*5 = 27 that does not fit

13. welshfella

now try c and d