Question

in an A.P. the 10th term is 47,sum of the 5th and 7th term is 52.find the A.P.

Answer 1

10th term,

A 10 = a+ 9d

47 = a +9d

a = 47 - 9d

5th term,

A5 = a + 4d

7th term,

A7 = a + 6d

Sum of 5th and 7th term = ( a + 4d) +( a + 6d)

52 = 2a + 10d

52 = 2 ( a + 5d )

a + 5d = 52/2 = 26

Putting value of a,

47 - 9d + 5d = 26

47 - 4d = 26

4d = 47 - 26 = 21

d = 21/4

Putting value of d in a,.

a = 47 - 9d

a = 47 - 9 ( 21 /4 ) = ( 188 - 189 ) / 4 = - 1 /4

First term = - 1/4

Second term = - 1 /4 + 21/4 = 20/4

Third term = 20/4 + 21 /4 = 41 /4

A. P. = - 1/4, 20/4, 41/4.......

Answer 2

This is the ans..
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