Question

求解答这道matlab题目。急用

Answer 1

第三题>> syms a b c x

>> f = a*x^2+b*x+c

f =

a*x^2 + b*x + c

>> solve(f)

ans =

-(b + (b^2 - 4*a*c)^(1/2))/(2*a)

-(b - (b^2 - 4*a*c)^(1/2))/(2*a)第五题

>> clear;

>> x = 0:20;

>> y = sin(x)+sqrt(x);

>> p = polyfit(x,y,5);

>> subplot(1,2,1)

>> plot(x,y,'b*')

>> subplot(1,2,2)

>> plot(x,polyval(p,x),'r')