Question

Factorize: $3a^2-1-2a$

• A. $(3a-1)(a+1)$
• B. $(a-1)(3a+1)$
• C. $(a-1)(3a-1)$
• D. $(3a+1)(a+1)$

Answer 1

The correct option is B $(a-1)(3a+1)$

$\Rightarrow 3a^2-1-2a$

$\Rightarrow 3a^2-2a-1$

$\text{Split}(-2a)\text{into two parts such that}$
$\text{their product is -3 and their sum is -2}$

$\Rightarrow 3a^2-3a+1a-1$

$\Rightarrow 3a(a-1)+1(a-1)$

$\Rightarrow (a-1)(3a+1)$