Question

An arithmetic sequence has t1 = 6 and common difference 2 find t12 and s12​

Answer 1

See below ~

Explanation:

Finding t₁₂ :

⇒ t₁₂ = t₁ + 11d

⇒ t₁₂ = 6 + 11(2)

⇒ t₁₂ = 6 + 22

⇒ t₁₂ = 28

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Finding S₁₂ :

⇒ S₁₂ = 12/2 × 2t₁ + (12 - 1)d

⇒ S₁₂ = 6 × 2(6) + 11(2)

⇒ S₁₂ = 6 × 12 + 22

⇒ S₁₂ = 6 × 34

⇒ S₁₂ = 204