How do I find ALL of the positive roots of exp(-0.2*x​)*cos(2*x)​-0.15*x^2+​1?

I enter this into Matlab but I only receive back one of its positive roots and I know it has at least three.

syms x,

y=exp(-0.2*x)*cos(2*x)-0.15*x^2+1;

sol=solve(y)

Answer 1

[Walter Roberson]

It has exactly three.

The easiest way is to plot the function, observe the approximate crossings, and run a numeric solver that is constrained to each range in turn.

[Rebecca]

What kind of numeric solver? I am very new to Matlab.