help with analysis of equations

if true
fplot('x^2-5*x*sin(3*x)+3',[0,10]);
disp('positive roots of the equation are')
x1=fzero('x^2-5*x*sin(3*x)+3',2)
x2=fzero('x^2-5*x*sin(3*x)+3',2.7)
end

determine the positive roots of the equation

x^2-5*x*sin(3*x)+3

    2.3656

    2.8435

I keep getting this two and my book says there should be 4 3.8;3.4;1.8;1.3

Answer 1

[Narges M]

Try this:

if true
   fplot('x^2-5*x*sin(3*x)+3',[0,10]);
   disp('positive roots of the equation are')
   hold on;
   plot(0:10,zeros(1,11), '--c');
   x1=fzero('x^2-5*x*sin(3*x)+3',2)
   x2=fzero('x^2-5*x*sin(3*x)+3',2.7)
   plot(x1,0,'rX', 'MarkerSize',8);
   plot(x2,0,'rX', 'MarkerSize',8);
end

As you see, this function only has these roots, and is different from the one in your book.