Identify the factors of x² - 4x - 21 = 0

Solution :

Given quadratic equation is:

x² - 4x - 21 = 0 is in the form of ax² + bx + c = 0

Now solving the equation by factorising

x² - 4x - 21 = 0

For factorising first split the middle term - 4x as - 7x and + 3x as -7x + 3x

= - 4x and (-7x) (3x) = - 21 x²

⇒  x² - 7x + 3x - 21 = 0

⇒  x(x - 7) + 3(x - 7) = 0

⇒  (x + 3) (x - 7) = 0

Hence. the factors of  x² - 4x - 21 = 0 are (x + 3) and (x - 7).

Identify the factors of x² - 4x - 21 = 0

Summary:

The factors of the given quadratic equation x² - 4x - 21 = 0 are (x + 3) and(x - 7).