Let a₁, a₂, ..........., a₂₁ be an AP such that …. If the sum of this AP is 189, then a₆a₁₆ is equal to :

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Sequences and Series

JEE Main 2021 · 1 Sep, Evening shift · Q5223

MathematicsMedium178×since 2002Q5223

Let a₁, a₂, ..........., a₂₁ be an AP such that

\sum\limits_{n = 1}^{20} {{1 \over {{a_n}{a_{n + 1}}}} = {4 \over 9}}

. If the sum of this AP is 189, then a₆a₁₆ is equal to :

JEE Main 2021 · 1 Sep, Evening shift · Q5223

MathematicsMedium178×since 2002Q5223

Let a₁, a₂, ..........., a₂₁ be an AP such that

\sum\limits_{n = 1}^{20} {{1 \over {{a_n}{a_{n + 1}}}} = {4 \over 9}}

. If the sum of this AP is 189, then a₆a₁₆ is equal to :