,-12,will be-77? Find the sum of this A.P. upto the-,ermi- 77.-3. The

1.	,-12,will be-77? Find the sum of this A.P. upto the-,ermi- 77.-3. The sum of first n terms of an A.P. whose first term is 8 and the common difference isto the sum of first 2n terms of another A.P. whose first term is - 30 and20 is equalcommon difference is 8. Find nINCERT EXEMPLAR74 The students of a schooldid
Answer» Sum of first n terms Sn=n/2[2a+(n-1)*d]n/2[2×8+(n-1)×20]=2n/2[2×-30+(2n-1)×8]16+20n-20=2(-60+16n-8)-4+20n=2(-68+16n)-2+10n=-68+16n66=6nn=11 What is value of n in second AP bro

,-12,will be-77? Find the sum of this A.P. upto the-,ermi- 77.-3. The sum of first n terms of an A.P. whose first term is 8 and the common difference isto the sum of first 2n terms of another A.P. whose first term is - 30 and20 is equalcommon difference is 8. Find nINCERT EXEMPLAR74 The students of a schooldid

Answer»

Sum of first n terms Sn=n/2[2a+(n-1)*d]n/2[2×8+(n-1)×20]=2n/2[2×-30+(2n-1)×8]16+20n-20=2(-60+16n-8)-4+20n=2(-68+16n)-2+10n=-68+16n66=6nn=11

What is value of n in second AP bro