Question

If $a+b+c=6$ and $ab+bc+ca=16$, find the value of $a^2+b^2+c^2$.

• A. 4
• B. 6
• C. 10
• D. 36

Answer 1

The correct option is A 4

Given $a+b+c=6$ and $ab+bc+ca=16$
Using the formula,
$(a+b+c{)}^2=a^2+b^2+c^2+2(ab+bc+ca)$
$6^2=a^2+b^2+c^2+2\left(16\right)$
$36=a^2+b^2+c^2+32$
$\Rightarrow a^2+b^2+c^2=36-32=4$