rs = seq(23, 26, length.out=100)
real_pt = c()
for( r in rs ){
    pr = polyroot( c(160*(r-1), 8*(r+10), 41, 3) )
    crt_1 = pr[1] # by inspection these are the two complex roots
    crt_2 = pr[3]
    real_pt = c(real_pt, Re(pr[1]))
}
plot(rs, real_pt, type='l', xlab='r', ylab='real part of root')
abline(h=0, col='red')
grid()