Question

Facterise the following expression using the identity (x+a) (x+b)
1.x²+13x+40
2. x²+12x+27
3.x²-7x-30
4.x²-5x-24​

Answer 1

Answer:

1. $(x + 8)(x + 5)$

2. $(x + 9)(x + 3)$

3. $(x-10)(x+3)$

4. $(x-8)(x+3)$

Step-by-step explanation:

1.

  $x^{2} + 13x + 40$

= $x^2 + 8x + 5x + 40$

= $x(x + 8)+5(x + 8)$

= $(x + 8)(x + 5)$

Ans:- $(x + 8)(x + 5)$

2.

  $x^2 + 12x + 27$

= $x^{2} + 9x + 3x + 27$

= $x(x + 9) + 3(x + 9)$

= $(x + 9)(x + 3)$

Ans:- $(x + 9)(x + 3)$

3.

  $x^{2} - 7x - 30$

= $x^{2} -10x + 3x - 30$

= $x(x-10)+3(x-10)$

= $(x-10)(x+3)$

Ans:- $(x-10)(x+3)$

4.

  $x^{2} - 5x - 24$

= $x^{2} - 8x + 3x - 24$

= $x(x - 8) + 3(x-8)$

= $(x-8)(x+3)$

Ans:- $(x-8)(x+3)$