Given:
The expression is:

To find:
The a monomial so that the trinomial may be represented by a square of a binomial.
Solution:
If an expression is
, then be need to add square of half of coefficient of x, i.e.,
in the given expression to make in perfect square.
We have,

Here, coefficient of b is 20,so wee need to add square of half of coefficient of b, i.e.,
.


Therefore, we need to add 100 to make
a perfect square binomial.