Calculus 10th Edition

$a) 4.$ $b) 64.$ $c)64.$
a) By Theorem $1.3:$ $\lim\limits_{x\to c} p(x)=p(c)$ $\lim\limits_{x\to1}(5-x)=5-1=4.$ b)By Theorem $1.3:$ $\lim\limits_{x\to c} p(x)=p(c)$ $\lim\limits_{x\to4}x^3=4^3=64.$ c)By Theorem $1.5: \lim\limits_{x\to c}(f(g(x)))=f(\lim\limits_{x\to c}g(x)).$ $\lim\limits_{x\to1}g(f(x))=g(\lim\limits_{x\to1}f(x))=g(4)=64.$