Write the factors of the quadratic equation: x^2 - 4x-21=0

(x - 7) (x + 3) = 0

Step-by-step explanation:

To factorise the quadratic

Consider the factors of the constant term ( - 21) which sum to give the coefficient of the x - term ( - 4)

The factors are - 7 and + 3, since

- 7 * 3 = - 21 and - 7 + 3 = - 4, thus

(x - 7) (x + 3) = 0 ← in factored form