Arithmetic Sequence Equation

Question

Find the first four terms of the sequence:  I Don't know were to begin I know it should be a fraction?

 

Question is :   a_n = (-1)ⁿ⁺¹ 4n

 

a_{1 = ?}

 

a_{2 = ?}

 

a_{3 = ?}

 

a_{4 = ?}

   

Answer 1

No fractions involved--how is it that you think you know "it" should be a fraction?

 

To get first term, substitute n=1 into the formula; you get -4 (because (-1) raised to power 2 is positive 1 coefficient of 4(1).

To get second term, substitute n = 2 & you get -8

 

It is hoped that you can calculate the next two terms, by substituting n=3 & n=4 into general formula for term #n.

 

When you are given a formula by which to generate terms, you begin with n=1, continue with n=2, etc.  You should be able to understand this now.