Question

Why is the answer here (-∞, 6)
why 6

Answer 1

A function, f(x), is equal to the value of y (f(x)=y). So f(x) (or the value of y) is negative when x goes from negative infinity to 6.

Answer 2

Explanation:

Basically, because till x = 6, f(6) was less than 0.

They are asking the value of f(x), not x.

Thanks