Question

Factorise: $a^2+10a+25$

Answer 1

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

It can be written as $a^2+10a+25$

$a^2+5^2+2\times a\times 10=(a+5{)}^2=(a+5\left)\right(a+5)$

Hence, factors are $(a+5)(a+5)$.