There are five terms in AP. Sum of the squares of extremes is 104 and sum of terms is 30 then find common difference (d)?
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HELLO DEAR,
let common difference be ( d ),
and first term is ( a ).
let the five terms be (a + 2d) , (a + b) , a , (a - d) , (a - 2d)
GIVEN:- Sum of the squares of extremes is 104 .
so,
(a + 2d)² + (a - 2d)² = 104
=> a² + 4d² + 4ad + a² + 4d² - 4ad = 104
=> 2a² + 8d² = 104--------------( 1 )
also,
sum of terms is 30
so, a + 2d + a + d + a + a - d + a - 2d = 30
=> 5a = 30
=> a = 6 [ put in ------ ( 1 ) ]
we get,
2a² + 8d² = 104
=> a² + 4d² = 52
=> 6² + 4d² = 52
=> 4d² = 52 - 36
=> 4d² = 16
=> d² = 4
=> d = ±2
I HOPE IT'S HELP YOU DEAR,
THANKS
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