FACTORIZATION - USING PRODUCT AND SUM
FACTORIZATION - USING PRODUCT AND SUM
EXAMPLE 1
Factorize: X2 + 8x + 15
a= 1, b = 8, c = 15
Product = a × c
= 1 × 15
= 15
Sum = b
= 8
To get the product 15 we can multiply 3 and 5 and to get the sum of 15 we can add 3 and 5.
Therefore, the middle term 8x can be written as 3x + 5x.
X2 + 8x + 15 = X2 + 3x + 5x + 15
= (x2 + 3x) + (5x + 15)
= x(x + 3) + 5(x + 3)
= (x + 5) (x + 3) are the two factors
EXAMPLE 2
Factorize: 7X2 + 2x - 5
= 7× -5
= -35
= 2
Therefore, the middle term 2x can be written as -5x + 7x.
= (7X2 + 7x) – ( 5X+ 5)
= 7X(X + 1) – 5(X +1)
= (7X – 5)(X+1) are the two factors
EXAMPLE 3
Factorize: 3X2 - 5x + 2
a= 3, b = -5, c = 2
Product = a * c
= 3* 2
= 6
Sum = b
= -5
To get the product 6 we can multiply -3 and -2 and to get the sum of -5 we can add -3 and -2.
Therefore, the middle term -5x can be written as -3x - 2x.
3X2 - 5x + 2 = 3X2 -3x -2x +2
= (3X2 -3x)+(-2x+2)
= 3x(x-1) -2(x – 1)
= (3x-2)(x-1) are the two factors
EXAMPLE 4
Factorize: 2X2 - 3x - 2
a= 2, b = -3, c = -2
Product = a × c
= 2×-2
= -4
Sum = b
= -3
To get the product -4 we can multiply -4 and 1 and to get the sum of -3 we can add -4 and 1.
Therefore, the middle term -3x can be written as -4x + x.
2X2 - 3x – 2 = 2X2 -4x + x – 2
= (2X2 + x) – (4x + 2)
= x(2x + 1) – 2(2x + 1)
= (2x+1)(x-2) are the factors