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:

math expression


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 :

math expression

Here is a LiveMath document to illustrate this formula.

LIVEMath


Example 2:

Solve 2x2 = 4x + 3


Answer

Exercise

Solve 6r2 = 6r + 1 using the quadratic formula.


Answer



get MathTutorDVDs

Easy to understand math lessons on DVD. Try before you commit.
MathTutorDVD.com


Book mark this page in Del.icio.us, Furl, Digg, StumbleUpon, whatever...


Didn't find what you are looking for? Try search:


Need a break? Play a math game. Well, they all involve math... No, really!

dumbolf memoTST bola shadow factory mindfields trick-hoops-challenge crystal clear