(x-1)/(x+1)=(x+9)/3

Solution for (x-1)/(x+1)=(x+9)/3 equation:

D( x )

x+1 = 0

x+1 = 0

x+1 = 0

x+1 = 0 // - 1

x = -1

x in (-oo:-1) U (-1:+oo)

(x-1)/(x+1) = (x+9)/3 // - (x+9)/3

(x-1)/(x+1)-((x+9)/3) = 0

(x-1)/(x+1)+(-1*(x+9))/3 = 0

(3*(x-1))/(3*(x+1))+(-1*(x+9)*(x+1))/(3*(x+1)) = 0

3*(x-1)-1*(x+9)*(x+1) = 0

-x^2-7*x-12 = 0

-x^2-7*x-12 = 0

-1*(x^2+7*x+12) = 0

x^2+7*x+12 = 0

DELTA = 7^2-(1*4*12)

DELTA = 1

DELTA > 0

x = (1^(1/2)-7)/(1*2) or x = (-1^(1/2)-7)/(1*2)

x = -3 or x = -4

-1*(x+4)*(x+3) = 0

(-1*(x+4)*(x+3))/(3*(x+1)) = 0

(-1*(x+4)*(x+3))/(3*(x+1)) = 0 // * 3*(x+1)

-1*(x+4)*(x+3) = 0

( x+3 )

x+3 = 0 // - 3

x = -3

( x+4 )

x+4 = 0 // - 4

x = -4

x in { -3, -4 }