Question

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

Answer 1

Given:

$a+b=25$ and $a^2+b^2=225$

Using,

$(a+b{)}^2=a^2+2ab+b^2$

$(25{)}^2=225+2ab$

$625=225+2ab$

$2ab=625-225$

$2ab=400$

$\therefore ab=200$

Hence, the required value is $200$.