Limit Values

Calculus Level 3

Suppose $f(x) = x^4 + ax^2 + bx$ satisfies the following two conditions:

$\lim_{x \to 2} \frac{f(x)-f(2)}{x-2} = 4,\quad \lim_{x \to 1} \frac{f(x)-f(1)}{x^2-1} = 9.\$

What is the value of $b-a?$