An Important question based on Arithmetic progression Chapter of R.S Aggarwal book for ICSE & CBSE Board.
Here the sum of three constructive terms of an AP and the sum of the Squares of these term is given. you have to find the term.
This is the Question Number 6 Exercise 11 B of RS Aggarwal Solution.
Deepak BoraNewbie
The sum of three consecutive terms of an AP is 21 and the sum of the squares of these terms is 165. Find these terms.
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let three consecutive terms be a-d, a, a+d
where d is common difference
a-d+a+a-d=21
3a=21
a=7
(a-d)²+a²+(a+d)²=165
a²-2ad+d²+a²+a²+2ad+d²=165
3a²+2d²=165
147+2d²=165
2d²=18
d²=9
d=3
a-d=4
a+d=10
the terms are 4,7,10