Consider the function \(f(u)\), \(g(u)\), \(h(u)\) as given below. Show that \((f \circ g) \circ h = f \circ (g \circ h)\) in the below case.
 
\(f(u) = u - 1\), \(g(u) = 3u + 1\) and \(h(u) = u^2\)
 
Proof:
 
\(f \circ g\) \(=\) ii
 
\((f \circ g) \circ h\) \(=\) iii - - - - - - - (I)
 
\(g \circ h\) \(=\) iii+i
 
\(f \circ (g \circ h)\) \(=\) iii - - - - - - - (II)
 
Equation (I) Equation (II)
 
Hence, proved.