Question

x/(x^2-16)-6/(x^2+5x+4)

Answer 1

Find the common denominator and add:

x/(x^2-16)-6/(x^2+5x+4)
=x/((x+4)(x-4)) - 6/((x+4)(x+1))
=[x(x+1)-6(x-4)]/[(x+4)(x-4)(x+1)]
=[x²-5x+24]/[(x+4)(x-4)(x+1)]
The numerator cannot be factored.