If: $a + b + c = 14$ and $a^2 + b^2 + c^2 = 96$, then $(ab + bc + ca)$ is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 50
We use the identity:
$(a+b+c)^2 = a^2 + b^2 + c^2 + 2(ab+bc+ca)$
Given:
$a+b+c = 14 \Rightarrow (a+b+c)^2 = 196$
$a^2+b^2+c^2 = 96$
Substitute:
$196 = 96 + 2(ab+bc+ca)$
$2(ab+bc+ca) = 100$
$ab+bc+ca = 50$