If a + b + c = 16, ab + bc + ac = 81, what is the value of a2 + b2 + c2?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 94.
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca)
According to the given question,
(16)2 = a2 + b2 + c2 + 2(81)
⇒ a2 + b2 + c2 = 256 - 162
⇒ a2 + b2 + c2 = 94