Sstrhsrtj

Hi People I am at a lost how to add the arrows I want to this image. Below is the image/ minimal example and my goal as well. I need help adding the arrows:

documentclass{article}



usepackage{tikz,geometry}



begin{document}



begin{minipage}{.5textwidth}

begin{tikzpicture}

draw[->] (-.5,0)--(6,0) node[below] {$x$};

draw[->] (0,-.5)--(0,3.5) node[left] {$y$};

draw [red,<->,thick] plot [smooth,tension=.7,samples=200] coordinates { 

 (.5,1) (1.25,.5) (2.75,1) (4.5,2.5) (6,1.75) };

filldraw[black] (1.25,.5) circle (2pt) node {$$};

filldraw[black] (4.5,2.5) circle (2pt) node {$$};

draw (1.25,0) node[below] {scriptsize $a$} -- (1.25,.5) -- (0,0.5) node 

  [left] {scriptsize $f(a)$};

draw (4.5,0) node[below] {scriptsize $b$} -- (4.5,2.5) -- (0,2.5) node 

  [left] {scriptsize $f(b)$};

node at (2.75,-1) [align=left] {scriptsize If the input $a$ is less than 

  the input $b$,\ scriptsize then the output for $a$ is less than the\ 

  scriptsize output for $b$.};

end{tikzpicture}

end{minipage}

begin{minipage}{.5textwidth}

begin{tikzpicture}

draw[->] (-.5,0)--(6,0) node[below] {$x$};

draw[->] (0,-.5)--(0,3.5) node[left] {$y$};

draw [blue,<->,thick] plot [smooth,tension=.7,samples=200] coordinates { 

  (.5,2.5) (1.25,2.6) (2.75,1) (4.5,.5) (6,1.25)  };

filldraw[black] (1.25,2.6) circle (2pt) node {$$};

filldraw[black] (4.5,.5) circle (2pt) node {$$};

draw (1.25,0) node[below] {scriptsize $a$} -- (1.25,2.6) -- (0,2.6) node 

 [left] {scriptsize $f(a)$};

draw (4.5,0) node[below] {scriptsize $b$} -- (4.5,.5) -- (0,.5) node 

 [left] {scriptsize $f(b)$};

node at (2.75,-1) [align=left] {scriptsize If the input $a$ is less than 

  the input $b$,\ scriptsize then the output for $a$ is greater than the\ 

  scriptsize output for $b$.};

end{tikzpicture}

end{minipage}



end{document}

This outputs:

I am trying add the "increasing" and "decreasing" arrows as in:

Like this?

documentclass{article}

usepackage{geometry}

usepackage{tikz}

usetikzlibrary{shapes.arrows}

begin{document}



begin{minipage}{.5textwidth}

begin{tikzpicture}[font=scriptsize ]

draw[->] (-.5,0)--(6,0) node[below] {$x$};

draw[->] (0,-.5)--(0,3.5) node[left] {$y$};

draw [red,<->,thick] plot [smooth,tension=.7,samples=200] coordinates { 

 (.5,1) (1.25,.5) (2.75,1) (4.5,2.5) (6,1.75) };

filldraw[black] (1.25,.5) circle (2pt) coordinate (start);

filldraw[black] (4.5,2.5) circle (2pt) coordinate (end);

path (start) -- (end) node[midway,above,draw=red,single arrow,fill=red!20,sloped]{increasing};

draw (1.25,0) node[below] {$a$} -- (1.25,.5) -- (0,0.5) node 

  [left] {$f(a)$};

draw (4.5,0) node[below] {$b$} -- (4.5,2.5) -- (0,2.5) node 

  [left] {$f(b)$};

node at (2.75,-1) [align=left] {If the input $a$ is less than 

  the input $b$,\ then the output for $a$ is less than the\ 

  output for $b$.};

end{tikzpicture}

end{minipage}

begin{minipage}{.5textwidth}

begin{tikzpicture}[font=scriptsize]

draw[->] (-.5,0)--(6,0) node[below] {$x$};

draw[->] (0,-.5)--(0,3.5) node[left] {$y$};

draw [blue,<->,thick] plot [smooth,tension=.7,samples=200] coordinates { 

  (.5,2.5) (1.25,2.6) (2.75,1) (4.5,.5) (6,1.25)  };

filldraw[black] (1.25,2.6) circle (2pt) coordinate (start);

filldraw[black] (4.5,.5) circle (2pt) coordinate (end);

path (start) -- (end) node[midway,above,draw=blue,single

arrow,fill=blue!20,sloped]{decreasing};

draw (1.25,0) node[below] {$a$} -- (1.25,2.6) -- (0,2.6) node 

 [left] {$f(a)$};

draw (4.5,0) node[below] {$b$} -- (4.5,.5) -- (0,.5) node 

 [left] {$f(b)$};

node at (2.75,-1) [align=left] {If the input $a$ is less than 

  the input $b$,\ then the output for $a$ is greater than the\ 

  output for $b$.};

end{tikzpicture}

end{minipage}

end{document}