Question

What is the common difference of an arithmetic sequence defined by the formula an=2n−4?

Answer 1

Answer:

d = 2

Step-by-step explanation:

Generate the first few terms

a₁ = (2 × 1) - 4 = 2 - 4 = -2

a₂ = (2 × 2) - 4 = 4 - 4 = 0

a₃ = (2 × 3) - 4 = 6 - 4 = 2

a₄ = (2 × 4) - 4 = 8 - 4 = 4

d = 0 - (- 2) = 2 - 0 = 4 - 2 = 2

Answer 2

Answer:

Common difference = 2.

Step-by-step explanation:

The general formula for an arithmetic sequence is

 an = a1 + d(n-1) where d = the common difference. This can be rearranged to:

an = dn - d + a1

So comparing:

an =  2n - 4 with the above we see that d = 2.