Question

If $a+b=25$ and $a^2+b^2=225$, then find ab.

• A. 214
• B. 204
• C. 200
• D. 180

Answer 1

The correct option is C 200

Given,
$a+b=25$
$a^2+b^2=225$
$ab=?$
We know that, $(a+b{)}^2=a^2+b^2+2ab$
${25}^2=225+2ab$
$\Rightarrow 2ab=625-225$
$\Rightarrow 2ab=400$
$\Rightarrow ab=200$