When you have an arithmetic sequence such as 10,15, 20, 25, 30, the function can be represented as f(x)= 5x+5. Where do you get the plus 5???

Question

Help on algebra problem. The arithmetic sequence is 5, 10, 15, 20, 25, 30... The function that represents it is f(x)=5x+5. Where do you get the +5. Please help!

Answer 1

Hi Liz,

 

I think you get the plus five because you want to start the sequence with x=0 (or a zeroth term if you will).

 

If you need to start with zeroth term you need the five because it can't be done with out that.

 

If you start with the first term being x=1, however you wouldn't need the five. It would just be 5x, or 5 times the number of the term

5*fierst(1)

5*second(2)

5*third(3)

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5*the xth term. But this won't allow you to represent the first term that's why you would have to have + 5