Question

Find th sum of 26 terms of an AP in which d=7 and 22nd term is 148​

Answer 1

Answer:

1661 is the answer

Step-by-step explanation:

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Answer 2

Answer:

2301 is the answer.

Step-by-step explanation:

Recall the sum formula:

$S_n=\frac{n}{2}(2a+(n-1)d)$

And the formula for nth term:

$a_n=a+(n-1)d$

According to the question,

d=7

$a_{22}=148$

We have to find $S_{26}$

Substitute 26 and the value of d in the sum formula

$S_{26}=\frac{26}{2}(2a+(25*7))$

$=13(2a+175)$        -----(1)

The unknown term in the above equation is 'a'.

We know that $a_{22}=148$

Hence substitute the formula for the nth term

$a+(21*7)=148$

$a+147=148$

$a=1$

Hence, we have found the value of 'a'.

Substitute this value in the sum equation 1.

$S_{26}=13((2*1)+175)$

$=13(177)$

=2301

Therefore, your answer is 2301 .

Hope it helps.