arithmetic sequence

Question

find a formula for the nth term in this arithmetic sequence:

a₁=8, a₂=4, a₃=0, a₄=-4

Answer 1

x-4...........................

Answer 2

a_n = 8 - 4(n-1)

[ Note: a_n = a₁ + d(n-1) is the standard formula; here, d=-4 ]

For example, for n=4 (4th term):

a₄ = 8 - (4)(4-1)

a₄ = 8 - (4)(3)

a₄ = 8 - 12

a₄ = -4

Answer 3

a_n=a₁+(n-1)d

a_n=8+(n-1)(-4)

Answer 4

There's a formula for the nth term of an arithmetic sequence. You should look it up in your textbook (or other learning material). It's

a_n = a₁ + (n-1)d

where d is the common difference between successive terms.

For example, if the first term was 9 and the common difference was -2, the formula would be

a_n = 9 + (n-1)(-2)