How do I get this to plot correctly?

%%
% Constant Acceleration Calculator  

% Constant Velocity is = Initial Velocity + Constant Acceleration * Time
%Vi = initial velocity 
%dt = delta (t) or how long are we accelerating 
% ac = acceleration constant or holding the pedal down
% Vi + constant acceleration * delta(t)

Vi = input('Initial Velocity  ');
dt = input('Change in time  ');
ac = input('Constant acceleration ');

constant_velocity = Vi + dt * (ac);

y = linspace(-10,30); 
x = constant_velocity;
hold on
plot(x,y)
grid on 
fprintf('%f Meters per / Sec',y)

Answer 1

[KSSV]

%%
% Constant Acceleration Calculator  

% Constant Velocity is = Initial Velocity + Constant Acceleration * Time
%Vi = initial velocity 
%dt = delta (t) or how long are we accelerating 
% ac = acceleration constant or holding the pedal down

Vi = input('Initial Velocity  ');
dt = input('Change in time  ');
ac = input('Constant acceleration ');

t = -10:dt:30; 
constant_velocity = Vi + t * (ac);


x = constant_velocity;
hold on
plot(t, x)
grid on 
% fprintf('%f Meters per / Sec',y)