Question

sum of first 25 term of an arithmetic sequence is 250. find it's middle term and it' 13th term​

Answer 1

Answer:

Question:-

Sum of first 25 term of A.P. is 250.find middle term i.e. 13th term.

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Required Answer:-

Given:- S25=250

To Find:- t13=?

Solution:-

S25=250

Formula:- Sn=n/2x[2a+(n-1)d]

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

S25=25/2[2a+(25-1)d]

250=25/2[2a+24d]

250x2=25x2[a+12d]

500=50[a+12d]

500/50=a+12d

10=a+12d -(i)

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t13=?

Formula:- tn=a+(n-1)d

tn=a+(n-1)d

t13=a+(13-1)d

t13=a+12d -(ii)

From (i) and (ii),

t13=10 -[Both RHS of (i) and (ii) are equal]

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Hope it help you :)

Answer 2

Answer:

answer;  to find the MIDDLE TERM THERE'S AN EASY WAY TO DO IT                                                                                                 SINCE, S 25=250

         BRING 25 TO THE SIDE OF 250                                                                         i e, S=250/25=10                                                                                                                                               THIS IS THE EASIEST METHOD TO FIND THE MIDDLE TERM                                                                   NOW FOR THE 13TH TERM                                                                                               13TH TERM=10