if the sum of four numbers in A.P is24 and sum of thier squares is 164.then those numbers are
Last Activity: 11 Years ago
they are 3,5,7,9
let the four no be a-3d,a-d,a+d,a+3d.
a-3d+a-d+a+d+a+3d=24 (given)
4a=24
a=6.
(a-3d)2+(a-d)2+(a+d)2+(a+3d)2=164 (given)
2(a2+9d2)+2(a2+d2)=164. since (a+b)2+(a-b)2=2(a2+b2)
2(2a2+10d2)=164.
2a2+10d2=164/2=82.
2(6)2+10d2=82.
10d2=10.
d=±1.
therefore four numbers are 3,5,7,9
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