Derivative question calculus

Hi I need some help with steps :
Let f be the function defined for all real numbers such that f ' (x) = absolute value (x^2 - 4 ) / (x-2) . Then f is a decreasing function on interval :
answer was -inf I thought the x-2 canceled out so x+2 = 0 and x = -2 is critical pt

think about what you have left if the x-2 's canceled. The ab val of x+2 if x is negative is positive and decreasiong as the values get larger (less negative) abs -10+2 is 8 abs -5+2 is 3 Ok?