If the $7^{t h}$ and $13^{t h}$ terms of an AP are 34 and 64 respectively, then its $18^{t h}$ term would be ____

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Solution

The correct option is C 89
The $7^{t h}$ term of the A.P is
$a + 6 d = 34 - - - (1)$

The $13^{t h}$ term of the A.P is
$a + 12 d = 64 - - - (2) Solving (2) - (1), a + 12 d - a - 6 d = 64 - 34 6 d = 30 ⟹ d = 5 Substituting d i n (1) a + 6 (5) = 34 ⟹ a = 4 ∴ a_{18} = 4 + (17) 5 = 89$

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Similar questions

If $7^{t h}$ and $13^{t h}$ terms of an AP be 34 and 64, then its $18^{t h}$ term is :

7^{th}

13^{th}

18^{th}

If the $7^{t h}$ and $13^{t h}$ terms of an AP are 34 and 64 respectively, then the $18^{t h}$ term of the AP would be ___.

7 t h

13 t h

A . P

34

64

18 t h

7^{t h}

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