Page 3 - LN

Factorisation Method

In this method, we factorise the equation into two linear factors and equate each factor
to zero to find the roots of the given equation.

2
Step 1: Write given Quadratic Equation in the form of ax + bx + c = 0.
Step 2: Split the middle term bx as mx + nx so that the sum of m and n is equal to b and
the product of m and n is equal to ac.
Step 3: By factorisation we get the two linear factors (x + m) and (x + n)
2
ax + bx + c = 0 = (x + m) (x + n) = 0
Step 4: Now we have to equate each factor to zero to find the value of x.
Example 3 : Solve the quadratic equations by factorisation:-
2
(i) 6x - 5x - 6 = 0
2
Ans: The given equation is 6x -5x - 6 = 0
2
6x -9 x + 4x - 6 = 0
3x(2x - 3) + 2(2x - 3) = 0
(2x - 3)(3x + 2) = 0
2x - 3 = 0 or 3x + 2 = 0

x = or x =

Thus the roots of given quadratic equation are and

(ii)
Ans: The given equation is

= 0 or = 0

y = or y =

3