Question 83144
To change a normal quadratic into the completed square form, first take half the coefficient of x (10) and place it in a bracket like this:
{{{(x+5)^2}}}
Expanding this expression gives:
{{{x^2+10x+25}}}
Since we don't need the last term, we eliminate it by subtraction:
{{{(x+5)^2-25}}}
and finally you add whatever that last term (a) is:
{{{(x+5)^2-25+a}}}
This method applies to the second example even if the coefficient of x is not divisible by 2:
{{{(x+3/2)^2-9/4+b}}}