# Which term of AP 3,10,17...., will be 84 more than its 13th term

2
by anujasanthosh14

2015-11-09T20:45:23+05:30

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A = 3

d = 7 ,

13th term will be ,

xa13 = a + 12d

a13 = 3 + 12×7

a13 = 3+ 84 = 87

Since , 84 more than its 13th term ,so ,

value of term will be = 87 + 84 = 171

So value of term is 171

Now using ,

an = a+(n-1)d

171 = 3 + 7n - 7

171 + 4 = 7n

175/7 = n

n = 25 ,

So 25th term will be 84 more than its 13th term ,

Verification :-

a25 = a + 24 d

a25 = 3 + 24×7

a25 = 3 + 168 = 171
but ans is -25
2015-11-09T20:49:33+05:30
a = 3…………
d= 7……………
a13 = a + 12ddd.......,.……...
= 3 + 84……….…
= 87................
hence, 87+ 84………….
= 171……….
an= 3 + 7n -7…….…
171 = 7n - 4…........
7n = 175..............
n = 25.
but ans is -25