Unable to plot matrix multiples

So I'm trying to plot the sum of a matrix at 25 different values using the code below, but matlab gives me the error " Error using ^ One argument must be a square matrix and the other must be a scalar. Use POWER (.^) for elementwise power. ", Even though x technically is a scalar (right?). Note that i am NOT trying to simply multiply the matrix by a constant x. For x=2 I want to compute A*A (matrix multiplication).

clear all

A = [1.9 0.025;0.1 1.225];

v = [1;0];

for i = 1:25 answer = sum((A^i)*v); end

answer

x = (1:25);

y = sum((A^x)*v);

plot (x,y)

xlabel('# of growth periods')

ylabel('Total # of bacteria')

Answer 1

[Birdman]

A = [1.9 0.025;0.1 1.225];
v = [1;0]; 
for i = 1:25 
   answer(i) = sum((A^i)*v); 
end  
x = 1:25;
plot (x,answer)  
xlabel('# of growth periods')  
ylabel('Total # of bacteria')

[Lukas Lehrman]

Thank you for the answer! I've since ran into yet another problem. Now I'm trying to calculate a the value of an unknown that would generate the maximum value in a matrix, but i get the error "Subscripted assignment dimension mismatch".

pvalues = [0:0.01:1];
v = [1;0]; 
for i=1:length(pvalues)
    p=pvalues(i)
    A = [2-p 0.25*p;p (1.25-(0.25*p))];
    answer(i) = (A^25)*v;
end
max(answer)

I thought i could work around it, but it seems that it hasn't worked.

[Birdman]

pvalues = 0:0.01:1; 
v = [1;0]; 
for i=1:length(pvalues)  
    A = [2-pvalues(i) 0.25*pvalues(i);pvalues(i) (1.25-(0.25*pvalues(i)))]; 
    res = (A^25)*v; 
    val(i)=max(res);
end