Which domain restrictions apply to the rational expression?

add

(-x-2/9x^2-1) + (-5x+4/9x^2-1)

i meant for the numbers in the parenthesis separated by / to be fractions

Both expression have the same denominator: 9x²-1. Thus it must not be 0.

9x²-1 = (3x-1) (3x+1) = 0, resulting x=+-1/3.

Restrictions: x in R/{-1/3, 1/3}

Adding those expressions:

E = (-x-2) / (9x²-1) + (-5x+4) / (9x²-1) =

(-x-2-5x+4) / (9x²-1) = (-6x+2) / (9x²-1) =

(-2) (3x-1) / (9x²-1) = -2 / (3x+1)

E=-2 / (3x+1)