Question

In an AP:
(i) given a = 5, d = 3, an = 50, find n and Sn.
(ii) given a = 7, a13 = 35, find d and S13.
(iii) given a12 = 37, d = 3, find a and S12.
(iv) given a3 = 15, S10 = 125, find d and a10.
(v) given d = 5, S9 = 75, find a and a9
(vi) given a = 2, d = 8, Sn = 90, find n and an
(vii) given a = 8, an = 62, Sn = 210, find n and d.
(viii) given an = 4, d = 2, Sn = –14, find n and a.
(ix) given a = 3, n = 8, S = 192, find d.
(x) given l = 28, S = 144, and there are total 9 terms. Find a
NCERT Class X
Mathematics - Mathematics
Chapter _ARITHMETIC PROGRESSIONS

Answer 1

It is easy but it isn't possible to give all answers. Here is the first one.

3 ) a12 = 37
d = 3
Now,
a + 11d = 37
=> a + 11 (3)= 37
=> a + 33 = 37
=> a = 37 - 33 = 5.......(1)

Now,
S12 = 12/2 {2 (5)+(12-1)3}
=> 6 {10+(11 × 3)}
=> 6 (10 + 33)
=> 6 × 43 = 258........ (2)


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Answer 2

Answer:

I hope it is helpful.....................