If (a + b + c) = 13, and (ab + bc + ca) = 54, find the value of (a2 + b2 + c2).
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 61.
We know,
(a + b + c)2 = (a2 + b2 + c2) + 2(ab + bc + ca)
According to the question;
⇒ 132 = (a2 + b2 + c2) + 2(54)
⇒ 169 - 108 = a2 + b2 + c2
⇒ a2 + b2 + c2 = 61