The sum of the squares of three numbers is 138, while the sum of their products taken two at a time is 131. Their sum is:
Choose the correct choice from the following
A) 20 B) 30 C) 40 D) 50 E) None of these
Let the numbers be a, b and c.   Then, a2 + b2 + c2 = 138 and (ab + bc + ca) = 131.   (a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca) = 138 + 2 x 131 = 400.   (a + b + c) = 400 = 20   20nswer:20
<result>A</result>
The sum of the squares of three numbers is 138, while the sum of their products taken two at a time is 131. Their sum is: