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Find the three numbers in A.P., …

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Find the three numbers in A.P., whose sum is 15 and the sum of whose squares is 77.
  • 1 answers

Yogita Ingle 5 years, 1 month ago

Let the three numbers in AP be a-d, a, a+d

Then, 

sum = a-d+a+a+d=15

3a = 15

So, a = 5

Also, Sum of squares = 83

(a-d)2+a2+(a+d)2=83

(5-d)2+25+(5+d)2=83

25+d2-10d+25+25+d2+10d=83

75+2d2=83

2d2=8

d=+2 or -2

When d = 2,

The numbers are 3, 5, 7

When d = -2,

The numbers are 7, 5, 3

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