Question

If $a+b+c=9$ and $ab+bc+ca=26$, then the value of $a^2+b^2+c^2$ is

• A. $29$
• B. $52$
• C. $81$
• D. None

Answer 1

The correct option is A $29$

Given, $a+b+c=9$......(1) and $ab+bc+ca=26$.......(2).

Now we have,

$\Rightarrow$$a^2+b^2+c^2=(a+b+c{)}^2-2(ab+bc+ca)$

$\Rightarrow$$a^2+b^2+c^2=(9{)}^2-2\times 26=81-52=29$.