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

Question

anonymous · Answer

where r the options?

amoodarya · Answer

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

anonymous · Answer

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

welshfella · Answer

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

welshfella · Answer

which of the options will fit that?

anonymous · Answer

a?

amoodarya · Answer

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

welshfella · Answer

no not a

anonymous · Answer

Oh! I thinks it's b!

welshfella · Answer

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

anonymous · Answer

An-1=5

welshfella · Answer

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

welshfella · Answer

now try c and d