Sunday, January 17, 2010

Form 4/Topic 2 - QUADRATIC EXPRESSIONS & QUADRATIC EQUATIONS.

2.1 QUADRATIC EXPRESSION.
1. Quadratic Expression is in the form of ax2+ bx + c where a,b,c are integers (positive or negative),
e.g - x2+3x +2,        x2-5x +4 ,       x2+5x -6  .

2. In this topic, you are supposed to factorise quadratic expressions.
    Factorisation of Quadratic Expression:
   
    (a) x2 + 3x + 2 = (x + 2)(x + 1) ... using factors of 2 (1 x 2)
    (b) x2 + 3x - 4 = (x + 4)(x - 1)  ... using factors of 4 (1 x 4)
    (c) x2 - 3x - 4 = (x - 4)(x + 1)  ... using factors of 4 (1 x 4)
    (d) x2 - 5x + 4 = (x - 4)(x - 1)  ... using factors of 4 (1 x 4)
    (e) x2 - 4x + 4 = (x - 2)(x - 2)  ... using factors of 4 (2 x 2)

**Please refer to your teachers or someone else who knows about factorisation if you have problems with the technique of factorising...

2.2  QUADRATIC EQUATIONS.
1.  Quadratic Equations are in the form of  ax2+ bx + c = 0 where a,b,c are integers (+ve or -ve).
2.  You are supposed to solve quadratic equations by factorisation, e.g. 

(a)      x2 + 3x + 2 = 0               
(x + 2)(x +1) = 0               
(x + 2) = 0  or  (x + 1) = 0                
x = -2   or  x =  -1  

(b)      x2 + 3x - 4 = 0         
(x + 4)(x - 1) = 0           
(x + 4) = 0  or  (x - 1) = 0           
 x = -4   or  x = 1  

(c)      x2 - 5x - 6 = 0           
(x - 6)(x + 1) = 0             
(x - 6) = 0  or (x + 1) = 0              
x = 6  or  x = -1  

(d)     x2 - 9x + 14 = 0             
(x - 7)(x - 2) = 0           
(x - 7) = 0  or  (x - 2) = 0           
 x = 7  or  x = 2   

 Happy Learning.... Have a nice day !! 


2 comments:

Momento97 said...

how to solve this
-3k^2+4k-1

DESS said...

(-3k + 1)(k - 1)= 0
(-3k + 1)= 0 or (k - 1)= 0
k = 1/3 or k = 1.

Have a nice day...