Question

In an A.P if a=5, d=3 then n, Sn respectively​

Answer 1

$\large{\boxed{\bf{Answer}}}$

• n = 16

• Sn = 440

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Given :-

• An AP whose a = 5 , d = 3 , an = 50

To Find :-

• n, Sn

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★ Let's find n

=> a + (n -1)d = 50

=> 5 + (n - 1)3 = 50

=> 5 + 3n - 3 = 50

=> 2 + 3n = 50

=> 3n = 50 - 2

=> 3n = 48

=> n = 48/3

=> n = 16

★ Now, let's find Sn

• Sn = n/2 {2a + (n - 1)d}

Sn => 16/2 {2(5) + (16 - 1)3}

Sn => 8 {10 + 45}

Sn => 8 × 55

Sn => 440

Hence, n and Sn are 16 and 440 respectively.

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