Question: what is the difference between f(0) and f(x)=0?
Answer: With the three bar equal sign, f(x) has been defined as zero and it will always be zero. Originally Answered: What is the difference between f(x) ≡0 and f(x) =0? The first symbol means that f(x) is the zero function. The second means there is at least one value of x whereby f maps x to 0.