Graphing using Matlab. How would you graph a function using matlab?

I am wondering how can you graph a function in MatLab? This is how I do it but the code doesn't work

% for matrix A
a = 24;
b = 4.8;
c = - 0.5 ;
d  =0.43
%y= a+bx 
hold on
for i = 0:20
    y = a + b*i
    plot(i,y)
    end

% now y = a + b*x + c*x^2
% and y = a + b*x +c*x^2 +d*x^3
% how would you graph these function? 

Answer 1

[Stephan]

a = 24;
b = 4.8;
ii = 0:20;
y = a + b.*ii;
plot(ii,y)