8.1–Solving quadratic equations by completing the square A ...

Ex. 1
Solve by completing the square:
1. *Recall the standard form of a quadratic equation and label
each term . Now let’s complete the
square. First, divide by a: . That
leaves us with . Second, move c:
. Third, take half of b (half of 4 is 2), square
it (2 squared is 4), and add it to both sides:
. Fourth, write the left side as a
perfect square (in other words, factor it): .
Fifth, take the square root of both sides of the equation and
solve: , . Since you
can’t take the square root of 10 evenly, leave it as a radical
and don’t forget the ± in front of it (you always need that
when taking the square root of a number). Now isolate the
x and get .