\(p = 
      Plot[3 + 1.5 \((x - 0.5)\) \((x - 1.5)\) \((x - 2.5)\), \ {x, 0.5, 3}, 
        \ PlotRange -> {{\(-1.5\), 3.5}, {\(-1\), 6}}, AxesOrigin -> {0, 0}, 
        
	Ticks -> False]\)

\(b\  = \ 
      Graphics[{
		GrayLevel[ .75], Rectangle[{0.5, 1}, {1.5, 2.75}], 

          		GrayLevel[0], 
          Line[{{0.5, 0}, {0.5, 2.75}, {1.5, 2.75}, {1.5, 0}}], 
		
          Line[{{0.5, 1}, {1.5, 1}}], 
		Line[{{1.5, 2.0}, {2.5, 2.0}}], 

          		Line[{{2.5, 0}, {2.5, 3.0}, {3.0, 3.0}, {3.0, 0.0}}], 
		
          Line[{{\(-0.1\), 2.75}, {0.0, 2.75}}], 
		
          Line[{{\(-0.1\), 1}, {0.0, 1}}]
	}]; 

    t\  = \ Graphics[{
          Text["u - y", \ {1, 1.75}, TextStyle -> {FontSlant -> Italic}], 
          
\ \ \ \ \ \ \ \ \ \ 
          Text[Subscript[x, 0], {0.5, \(-0.5\)}, 
            TextStyle -> {FontSlant -> Italic}], 
\ \ \ \ \ \ \ \ \ \ 
          Text[Subscript[x, 1], {1.5, \(-0.5\)}, 
            TextStyle -> {FontSlant -> Italic}], 
\ \ \ \ \ \ \ \ \ \ 
          Text["...", {2.5, \(-0.5\)}], 
\ \ \ \ \ \ \ \ \ \ 
          Text[Subscript[x, n], {3.0, \(-0.5\)}, 
            TextStyle -> {FontSlant -> Italic}], 
\ \ \ \ \ \ \ \ \ \ 
          Text[Subscript[s, 1], {\(-0.25\), 2.65}, 
            TextStyle -> {FontSlant -> Italic}], 
\ \ \ \ \ \ \ \ \ \ 
          Text[Subscript[s, 1] - \ 
              \((u - y)\)/\((Subscript[x, 1] - \ Subscript[x, 0])\), {
              \(- .75\),  .9}, TextStyle -> {FontSlant -> Italic}]
		}]; 

    Show[p, b, t]\)