Using MATLAB to draw a function image, such as y = X. ^ 2-4 * x + 5, how to find the coordinates of the maximum point on the image

Using MATLAB to draw a function image, such as y = X. ^ 2-4 * x + 5, how to find the coordinates of the maximum point on the image

syms x
ff=x^2-4*x+5;
ff1=diff(ff);
xx=0:.2:4;yy=subs(ff,x,xx);
a1=double(solve(ff1));ya1=double(subs(ff,x,a1));
plot(xx,yy);
hold on
plot(a1,ya1,'b*');
Text (A1, ya1, 'minimum point');
There's only a minimum, opening up