3. The Quadratic Formula
Using the method of completing the square, we can derive a general formula for solving quadratic equations:
For any quadratic equation ax2 + bx + c = 0, the solutions for x can be found by using the quadratic formula:
Example 1:
Solve 2x2 - 7x - 5 = 0
Answer
By inspection, we can see that: a = 2, b = -7 and c = -5
Substituting these into the quadratic formula, we get :
Here is a LiveMath document to illustrate this formula.
Example 2:
Solve 2x2 = 4x + 3
Exercise
Solve 6r2 = 6r + 1 using the quadratic formula.
Didn't find what you are looking for on this page? Try search:
The IntMath Newsletter
Sign up for the free IntMath Newsletter. Get math study tips, information, news and updates each fortnight. Join thousands of satisfied students, teachers and parents!
Algebra Lessons on DVD
Easy to understand algebra lessons on DVD. See samples before you commit.
More info: Algebra videos
Book mark this page
Add this page to Del.icio.us, Furl, Digg, StumbleUpon, Google, whatever...
Need a break? Play a math game. Well, they all involve math... No, really!







