Solution
= Solution
Take $f(n)=g(n)=n^2$, so $h(n)=n^2$ but $(f\circ g)(n)=n^4$. The ratio $(f\circ g)(n)/h(n)=n^2$ is unbounded, precluding any eventual constant upper bound in <big O notation>. \b[False: in general $f\circ g\ne O(h)$.] This is a <counterexample> involving <function composition>, not pointwise addition.