Question

Dentify the factors of x2 − 4x − 21.

Answer 1

`(x - 7)(x + 3)`

Explanation:

`{x}^(2) - 4x - 21 \\ = {x}^(2) - (7 - 3)x - 21 \\ = {x}^(2) - 7x + 3x - 21 \\ = x(x - 7) + 3(x - 7) \\ = (x - 7)(x + 3)`

Answer 2

Identify the factors of x2 − 4x − 21.

`x^2-4x-21`

Factorise the equation

`\begin{gathered} x^2-4x-21 \\ x^2+3x-7x-21 \\ x(x+3)-7(x+3) \\ (x+3)(x-7) \end{gathered}`

The solutions of the equation

`(x+3)(x-7)`