How do I find all the positive roots of (e^(-.2x ))(cos(2x))-.15x^2+1

I only know how to do this with polynomials.

Answer 1

[Azzi Abdelmalek]

syms x,
y=exp(-.2*x )*cos(2*x)-.15*x^2+1
sol=solve(y)

[Rebecca]

How do you compute all three of its positive roots. When I enter this into Matlab I only get one of its positive roots.