Sum of products of three numbers taken two at a time is 131. Sum of squares of the three numbers is 138. What is the sum of the three numbers?  Choose the correct choice from the following choices:
A) 20	B) 88	C) 26	D) 18	E) 17
Explanation:   All the data given in the question points to the equation mentioned below:   Considering the three numbers to be a,b and c:   (a+b+c)2 = a2 + b2 + c2 + 2ab + 2bc + 2ca   Accordingly, substitute for a, b and c and solve:   =&gt; a2+b2+c2= 138, ab+bc+ac = 131. Thus, 2(ab+bc+ac)= 2*131= 
<gadget id="calculator">2*131</gadget>
<output>262</output>
262   (a+b+c)2= 138+262= 
<gadget id="calculator">138+262</gadget>
<output>400</output>
400.   Therefore, a+b+c= 20   20NSWER: 20
<result>A</result>
Sum of products of three numbers taken two at a time is 131. Sum of squares of the three numbers is 138. What is the sum of the three numbers?