You can use symbolic toolbox.

do something like that:

clc;

clear;

syms x

Answer = zeros(5,3,4);

% solving

for a = 1:5

for b = 2:4

S = solve (a*x.^4+b*x.^3+x+1==0,x);

Answer(a,b,1) = double(S(1));

Answer(a,b,2) = double(S(2));

Answer(a,b,3) = double(S(3));

Answer(a,b,4) = double(S(4));

end;

end;

%displaying roots(a=1, b)

figure;

hold on

A = Answer(1,1,:)

plot(A(:),'o')

A = Answer(1,2,:)

plot(A(:),'x')

A = Answer(1,3,:)

plot(A(:),'p')

hold off

Dear Valery Strotov, thank you for your nice answer. I need few more information on it. I want to connect all the roots i.e., 1st root of x in each case (a varies from 1 to 5 and b varies from 2 to 4) and get a line and similarly I want to connect 2nd root of x for each values of a and b in the range mentioned above and get a corresponding line etc till 4th root of x.

Dear Vemula, I think you must decide how to arrange the roots first. I mean, you must deside how to find the root#1, #2, #3 and #4 because they all have equal priority.

Ok, If you think that S(i) is i-th root than we can change old code a little bit

clc;

clear;

syms x

Answer = zeros(5,3,4);

for a = 1:5

for b = 2:4

S = solve (a*x.^4+b*x.^3+x+1==0,x);

Answer(a,b,1) = double(S(1));

Answer(a,b,2) = double(S(2));

Answer(a,b,3) = double(S(3));

Answer(a,b,4) = double(S(4));

end;

end;

figure;

A = Answer(:,:,1)

plot(A(:),'-o')

figure;

A = Answer(:,:,2)

plot(A(:),'-s')

figure;

A = Answer(:,:,3)

plot(A(:),'-*')

figure;

A = Answer(:,:,4)

plot(A(:),'-p')