give a reason the limit does not exist or compute its value
f(x)=[tex]\left \{ {{x^3 \\ x\leq 1}\atop {-4x=5 \\ x\geq 1}}\right.[/tex]

a) [tex]\lim_{x \to \-1} f_(x)[/tex]
b) [tex]\lim_{x \to \11} f_n(x)[/tex]