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 answers
A) 20 B) 40 C) 50 D) 60 E) 80
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 * 131= 
<gadget id="calculator">138 + 2 * 131</gadget>
<output>400</output>
400   (a + b + c)= âˆš400 = 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: