Question -
Answer -
Let the three terms of an A.P. be a – d, a, a + d
Sum of three terms = 21
=> a – d + a + a + d = 21
=> 3a = 21
=> a = 7
and product of the first and 3rd = 2nd term + 6
=> (a – d) (a + d) = a + 6
a² – d² = a + 6
=> (7 )² – d² = 7 + 6
=> 49 – d² = 13
=> d² = 49 – 13 = 36
=> d² = (6)²
=> d = 6
Terms are 7 – 6, 7, 7 + 6 => 1, 7, 13