If a2 + b2 + c2 = 300 and ab + bc + ca = 50 then what is the value of a + b + c ? (Given that a, b and c are all positive)
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 20
We know that,
⇒ a2 + b2 + c2 = 300
⇒ ab + bc + ca = 50
By using the identity,
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca)
⇒ (a + b + c)2 = 300 + 2 × 50
⇒ (a + b + c)2 = 400
⇒ a + b + c = 20