# how do quadratic equations work?

Dictionary.com defines a quadratic equation as one "containing a single variable of degree 2. Its general form is ax 2 + bx + c = 0, where x is the variable and a, b, and c are constants ( a ≠ 0)." Algebra.com provides a good explanation of how to solve quadratic equations see: http://www.algebra.com/algebra/homework/quadratic/lessons/Introduction_Into_Quadratics.lesson
foo
15 August 2011
foo
15 August 2011
You could also check out this video
foo
15 August 2011
In addition to solving quadratic equation by completing the square, you can also try factorising (i.e. putting it into brackets) and using the quadratic formula (which is given to you in GCSE exams but not in A-level exams).There are also two imprecise methods for solving quadratics and these should not be used unless you are specifically told to use them. The first is a graphical method. Providing your equation reads ... = 0 then you just have to draw the graph of y = {whatever the quadratic is} and where the graph crosses the x-axis are the solutions to the equation. Alternatively you can try a trial and improvement method whereby you just try different values for x and you try to achieve the value on the right hand side.
simonwilliams1978
18 August 2011
Factorising is the neat, elegant way of solving quadratics but it's not always possible. If this is the case then you only have two choices: either complete the square or use the formula. Using the formula will always work! Remember though not every quadratic equation has real solutions so if you end up with a negative number inside the square root (check the signs!!!) then there are no real solutions. Further Maths students: if this happens then you have an equation with complex solutions.
simonwilliams1978
18 August 2011