4th term of an arithmetic sequence is 23 and its 11th term is 65, what is its common difference
1 answer:
Answer:
d = 6
Step-by-step explanation:
The nth term of an arithmetic sequence is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₄ = 23 and a₁₁ = 65 , then
a₁ + 3d = 23 → (1)
a₁ + 10d = 65 → (2)
Subtract (1) from (2) term by term to eliminate a₁
10d - 3d = 65 - 23
7d = 42 ( divide both sides by 7 )
d = 6
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