Find the values of the coefficients a and b such that F(x) are cubic splines. \text { a. } F(x)=\left\{\begin{array}{ll} x^{3}-2 a x, & -1 \leq x \leq 0 \\

b x^{3}-x, & 0 \leq x \leq 2 \end{array}\right. \text { b. } F(x)=\left\{\begin{array}{cc} x^{3}+x+a, & -1 \leq x \leq 0 \\ x^{3}+b x, & 0 \leq x \leq 1 \end{array}\right.