Processing Math: Done

From Förberedande kurs i matematik 1

If we consider the squaring rule

x−a2=x2−2ax+a2 

and move a2 over to the left-hand side, we obtain the formula

x−a2−a2=x2−2ax 

With the help of this formula, we can rewrite (complete the square of) a mixed expression x2−2ax to a obtain a quadratic expression, x−a2−a2  .

The expression x2−2x corresponds to a=1 in the formula above and thus

x2−2x=x−12−1