f[x_]:=a+b x;
a=7;
b=1;
Plot[{f[x],7},{x,-3,3},AxesLabel->{"x","f[x]"},PlotRange->{{-3,3},{-5,10}}]

f[x_]:=a+b x +c (x^2);
a=5;
b=1;
c=-3;
Plot[ f[x] ,{x,-3,3},AxesLabel->{"x","f[x]"},PlotRange->{{-3,3},{-2,15}}]

f[x_]:=5+1 x -3 (x^2)+7(x^4)-5(x^5) ;
 
Plot[ f[x] ,{x,-10,10},AxesLabel->{"x","f[x]"} ]

Plot[Sin[x],{x,0,4π}]

Plot[Cos[x],{x,0,4π}]

Plot[Tan[x],{x,0,4π}]

Plot[Cot[x],{x,0,4π}]

Plot[Sec[x],{x,0,4π}]

Plot[Csc[x],{x,0,4π}]

Plot[Exp[x],{x,-10,1}]

Plot[Sinh[x],{x,-10,10}]

Plot[Cosh[x],{x,-10,10}]

Plot[Log[x],{x,-10,30}]

Plot[{x,(x^2),(x^3),(x^4),(E^x)},{x,-10,30},PlotStyle->{Blue,Red, Orange,Green,Gray}]

Plot[{1/x,1/(x^2),1/(x^3),1/(x^4)},{x,-10,30},PlotStyle->{Blue,Red, Orange,Green}]

Plot[{x,2(x^2),5(x^3),3(x^4) },{x,0,1.2 },PlotStyle->{Blue,Red, Orange,Green }]

f[x_]:=-10+1 x -3 (x^2)+7(x^4)  ;
 
Plot[ f[x] ,{x,-2 ,2 },AxesLabel->{"x","f[x]"},AxesOrigin->{0,0} ]

Plot[(x^3)-(x^2)+.1,{x,-1 ,1.2 },AxesLabel->{"x","f[x]"},AxesOrigin->{0,0} ]