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if the sum of 4 terms of an AP. is 20.............n sum of their squares is 120...............find the terms!!!!!!! PLS EXPLAIN!!!!!!!!!!!!!!!

if the sum of 4 terms of an AP. is 20.............n sum of their squares is 120...............find the terms!!!!!!!


PLS EXPLAIN!!!!!!!!!!!!!!!

Grade:9

1 Answers

VIPUL GUPTA
52 Points
13 years ago

suppose four terms are (a+3x),(a+x),(a-x),(a-3x)

now sum op ap =20=4a;    =>a=5;

sum of squares of ap =120=(a+3x)2+(a+x)2+(a-x)2+(a-3x)2     => x=1 or x=-1,

in either case four nos turn out to be 2, 4, 6, 8.

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