[填空题]
Let $f(x)=x^{4}+5 x^{3}+a x^{2}+b x+2$ , for $x \in \mathbb{R}$ , where a, b are constants. The remainder when f(x) is divided by (x-1) is 6 , and the remainder when f(x) is divided by (x+2) is -6 . Find the value of a and the value of b . a = b =
