Question

find the roots of the quadratic equation by factorisation:x2-3x-4=0​

Answer 1

Answer:

Given:      x² - 3x - 4 = 0

⇒           x² - 4x + x - 4 = 0

⇒           x( x - 4) + 1( x - 4) = 0

⇒           (x + 1)(x - 4) = 0

∴ So there will be two values of x = -1 , 4

     

Answer 2

${x}^{2} - 3x - 4 = 0 \\ {x}^{2} - 4x + x - 4 = 0 \\ x(x - 4) + 1(x - 4) = 0 \\ (x + 1)(x - 4) = 0$

$x + 1 = 0 \\ x = - 1 \\ \\ and \\ \\ x - 4 = 0 \\ x = 4$