Basic limit

Calculus Level 3

$\large \lim _{ x \to 1}{ \frac { \sqrt { 4{ x }^{ 3 }+3x+2 } -\sqrt { 3{ x }^{ 2 }+x+5 } }{ { x }^{ 2 }+x-2 } } = \frac { a }{ b }$

If the equation above holds true for coprime positive integers $a$ and $b$ , what is $a + b$ ?