Prove that Big-O is transitive by relation. What does it mean by 'by relation'?
f(n)=O(g(n)) implies f(n) &lt;= c1*g(n)
g(n)=O(h(n)) implies g(n) &lt;= c2*h(n)
therefore, 
f(n) &lt;= c1*c2*h(n) = c3*h(n)

f(n) &lt;= c3*h(n) implies f(n)=O(h(n))