Question

Hlw Guys ☺

Plz Solve it.....!!

The Sum of First n terms of an AP is 210 and the Sum of its First n-1 term is 17,
If the First term is 3, then​ Write an AP.


@mary​

Answer 1

Answer:

To find the AP if the sum of first n terms of arithmetic progression is 210 and sum of its first (n-1) terms is 171. If the first term is 3 .

As we know that if AP has n terms,then after removing (n-1) terms,we are left with the last term.To find the AP if the sum of first n terms of arithmetic progression is 210 and sum of its first (n-1) terms is 171. If the first term is 3 . As we know that if AP has n terms,then after removing (n-1) terms,we are left with the last term. so, arithmetic progression is 3,7,11,15

Please mark it as brainliest :-P

Answer 2

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First term (a) = 3

We know that,

Sn = n/2(2a+(n-1)d)

Or,

Sn = n/2(a+l)

Last term = Sn - Sn-1 = 210 - 17 = 193

➡️Sn = n/2(3+193) = 210

=> 98n = 210

=> n = 210/98 ---- (I)

⏩⏩ I think any data is wrong here. Because number if terms cannot be in fraction.

$\large\red{\</em><em>boxed</em><em>{Hope\:it\:helps}}$