How to plot a simple function that has a variable?

The question I have is:

Write a MATLAB function

func(x,a) = x^2 + ax - 6

Use the function to plot, func(x,1), func(x,2) and func(x,3) on the same axes, for -10<x<10.

Im really confused how to define a as 1, 2 and 3 and how to substitute them into the function.

Answer 1

[madhan ravi]

Read about fplot()

syms x
for a=1:3
func = x^2 + a*x - 6 ;
fplot(func,[-10 10])  %ranging from -10 to 10
hold on
end

[Jonathan Whiting]

Thanks alot :)

[madhan ravi]

Anytime :)

[Stephen23]

I very much doubt that this assignment was intended to require the Symbolic Toolbox. The assignment "Write a MATLAB function ..." requested an actual MATLAB function:

https://www.mathworks.com/help/matlab/functions.html

and this is what the other answers provide.

Answer 2

[TADA]

func = @(x,a) x^2 + a*x - 6;
x = -10:0.1:10;

for a = 1:3
    plot(x, func(x,a ));
    hold on;
end

Answer 3

[Stephen23]

You can do this very simply by defining a normal function handle:

>> F = @(x,a) x.^2 + a*x - 6;
>> X = -10:.1:10;
>> plot(X,F(X,1),'r', X,F(X,2),'g', X,F(X,3),'b')