Arithmetic Series question

[Peaches04]

Need help with this problem

How many terms of the arithmetic sequence 2,4,6,8, ... add up to
60,762?

 

[TchrWill]

The sum of n even numbers is n(n + 1).

Therefore, n(n + 1) = 60,762 or n^2 + n - 60,772 = 0

Solve by means of the quadratic equation

 

[ting]

Is the formula for the sum of the nth terms of an arithmetic sequence in your book.

The nth term of your sequence is 2n

So you have


60762 = (n/2)(2 + 2n).


Solve for n


n^2 + n - 60762 = 0


There is probably a 'better' way.

 

[Guest]

You can always plug in numbers . Or you can graph the equation on your graphing calculator (if you have one of course)

 

[Guest]

the answer is 246. I made a program on my calculator to solve this kind of stuff. What I really wanted to do was show you a graph but I don't know how, hope this helped