© 2004  Rasmus ehf

Equations II

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Lesson 3.

Second degree equations

Example 1

	First we simplify and divide by the coefficient of the variable (5)  on both sides of the equation
	Finally we get this result after simplifying

If an equation contains a variable squared (to the  power of 2 )
such as		or		after it has been simplified, it is called a second degree equation.

We know that the square root of a number is one of the two equal factors of that number (the square root of x is the inverse of x² ). 

We see that:

and

Both (-3)²  and  3² = 9 

Example 2

  To solve equations like this, begin by factorising. 

x(x - 5) = 0      If either of the factors is 0, the equation is true. 

0(x - 5) = 0    or  x(0) = 0

     
The result is x = 0 .

or

   
The result is x - 5 = 0 or x = +5 .

or

When equations have more than one possible solution,
the solutions are labelled		and		to avoid confusion.

Try Quiz 3 on Equations 2.  
Remember to use the checklist to keep track of your work.