(9s^2+9s)/(18s^2+81s)

Solution for (9s^2+9s)/(18s^2+81s) equation:

D( s )

18*s^2+81*s = 0

18*s^2+81*s = 0

18*s^2+81*s = 0

18*s^2+81*s = 0

DELTA = 81^2-(0*4*18)

DELTA = 6561

DELTA > 0

s = (6561^(1/2)-81)/(2*18) or s = (-6561^(1/2)-81)/(2*18)

s = 0 or s = -9/2

s in (-oo:-9/2) U (-9/2:0) U (0:+oo)

(9*s^2+9*s)/(18*s^2+81*s) = 0

9*s^2+9*s = 0

9*s*(s+1) = 0

s+1 = 0 // - 1

s = -1

9*s*(s+1) = 0

18*s^2+81*s = 0

9*s*(2*s+9) = 0

2*s+9 = 0 // - 9

2*s = -9 // : 2

s = -9/2

9*s*(s+9/2) = 0

(9*s*(s+1))/(9*s*(s+9/2)) = 0

( 9*s )

9*s = 0 // : 9

s = 0

( s+1 )

s+1 = 0 // - 1

s = -1

s in { 0} 

s = -1