 |
 |
 |
|
 |
|
 |
|
 |
|
 |
|
 |
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
Contents
Factorising Quadratic Equations
Completing the Square method
|
Completing the Square Method Sometimes the roots of a quadratic equation cannot be obtained by simple factorisation. So, a more general method is used. This method, which is based on the fact that any quadratic equation may be written in the form of (x+p)2 = q, where p and q are real numbers, is known as completing the square method.
Example 1
x2 + 8x = -9 x2 + 8x + (4)2 = -9 + (4)2 (x + 4)2 = 7 x
+ 4
=
x = -4
+ x = -1.35 x = -6.65 (to 3 s.f.)
Example 2
Example 3
|
Solve
x2 + 8x + 9 = 0, giving your answers to 3 significant figures.
x2
+ 8x + 9 = 0
or x + 4 = 
