If x2 + y2 + z2 = 628 and xy + yz + zx = 24, then find the value of (x + y + z).
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 26.
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca)
According to the given question,
(x + y + z)2 = x2 + y2 + z2 + 2(xy + yz + zx)
⇒ (x + y + z)2 = 628 + 48
⇒ (x + y + z)2 = 676
⇒ (x + y + z) = 26