Tom K. answered 01/05/21
Knowledgeable and Friendly Math and Statistics Tutor
The vertical asymptotes mean that we have x+2 and x+6 as factors in the denominator. To have a horizontal asymptote of 4, the numerator and denominator have to have the same degree, and the leading coefficients of the numerator divided by the leading coefficient of the denominator must be 4.
The obvious polynomial fraction to use is
4x^2/((x+2)(x+6)) or 4x^2/(x^2+8x+12)