# What is the maximum value that the graph of y= x^2 -4x?

As $x$ increases without bound, ${x}^{2} - 4 x$ also increases without bound. (Another way of saying this is: ${\lim}_{x \rightarrow \infty} \left({x}^{2} - 4 x\right) = \infty$.) That means there is no upper bound and no maximum.