Use

minus−infinity[infinity]

or

infinity[infinity]

where appropriate to describe the behavior at each zero of the denominator and identify all vertical asymptotes.

f left parenthesis x right parenthesis equals StartFraction x squared minus 6 x minus 72 Over x squared minus 18 x plus 72 EndFractionf(x)=x2−6x−72x2−18x+72
Locate all zeros of the denominator. Choose the correct answer below.

A.

f has zeros of the denominator at

x equals 12x=12,

x equals 6x=6,

and

x equals negative 6x=−6.

B.

f has a zero of the denominator at

x equals 6x=6.

C.

There are no zeros of the denominator.

D.

f has zeros of the denominator at

x equals 12x=12

and

x equals 6x=6.