What should be added to the polynomial so that it becomes perfect square 4X square plus 8X?
By adding four we can make it perfect square
Thus it becomes a perfect square
But how do we get to this answer without any guess , here's the role of discriminant.
Any quadratic equation is of form
Here , discriminant
For perfect squares it is
So , we get
That's the answer
A perfect square is of form:
Let the unknown value be