2. Polynomials
easy

Factorise : $3 x^{2}-x-4$

Option A
Option B
Option C
Option D

Solution

 $3 x^{2}-x-4$

We have  $a =3$, $b =-1$ and $c =-4$ 

$\therefore  l+ m =-1 $ and $lm =3 \times(-4)=-12$

$\therefore $ $ l=-4$  and  $m =3 $

Now,          $3 x ^{2}- x -4=3 x ^{2}-4 x +3 x -4$

$=x(3 x-4)+1(3 x-4)=(3 x-4)(x+1)$

Thus, $3 x^{2}-x-4=(3 x-4)(x+1)$

Standard 9
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.