Sum of the squares of 3 no. is 138 and the sum of their products taken two at a time is 131. Find the sum?
Choose the correct choice from the following answers
A) 20	B) 21	C) 25	D) 26	E) 27

Rationale: "( a + b + c ) 2 = a 2 + b 2 + c 2 + 2 ( ab + bc + ca ) = 138 + 2 * 131 a + b + c = √ 400 = 20 a"
Answer: A