does the points show a function?

(1,-8) (2,-6) (3,-1) (4,-2) (5,-4)

No, these points do not show a function. A function is a set of ordered pairs where each x-value is paired with a unique y-value. In this case, both the x-values 2 and 4 are paired with the y-value -6 and -2 respectively, which violates the definition of a function.