Consider the function f$($x$)=$ x $3+3$x $2$ x $49$x $2.($a$)$ Find lim x$0$ f$($x$).($b$)$ Find lim x$3+$ f$($x$).($c$)$ Why can$$t we directly substitute in x $=0$ and x $=3$ right away to evaluate these limits$?$