{{{D=var('D') w=solve(64*D**2+16*D+1==0,D) print w

{{{id=1| #(i) omega = sqrt(20/5)

f = var('f')

solve(2*pi*f == omega, f) /// [f == (1/pi)] }}}

{{{id=2| #(ii) omega = sqrt(45/5)

f = var('f')

solve(2*pi*f == omega, f) /// [f == 3/2/pi] }}}

<p>sage seems to have troubles writing f = 3/2*pi</p>

{{{id=3| #(iii) omega = sqrt(65/5)

f = var('f')

a = solve(2*pi*f == omega, f) /// [ f == 1/2*sqrt(13)/pi ] }}}

{{{id=4|

/// 

D=var('D')
w=solve(64*D**2+16*D+1==0,D)
print w