Question

sum of 3 consevutive terms is 21 in A.P. if the sum of square of these terms is 165 find these terms

Answer 1

no be a,a+d,a+2d ,given a+a+d+a+2d=21 ,3a+3d =21,a+d =7 ,a2+a2+d2+2ad+a2+4d2+4ad = 165 ,3a2+5d2 +6ad = 165 solve these equation and find values

Answer 2

Hey buddy! Here's your answer!

Let the first term be a, and common difference d.

Let the terms be a - d, a, a + d

a - d + a + a + d = 21

3a = 21

a = 7

(a - d)² + a² + (a + d)² = 165

(7 - d)² + 7² + (7 + d)² = 165

49 - 14d + d² + 49 + 49 + 14d + d² = 165

147 + 2d² = 165

2d² = 18

d² = 9

d = +- 3

Terms are 4, 7, 10 or 10, 7, 4

Hope this helps! :)