power rule
can be rewritten as
so
Actually, while the "power law" is one of the most important laws for differentiation, here I think it is "overkill".
One of the first things you should have learned about the derivative is that the derivative of a linear function is just its slope.
(Most people learn the derivative as "slope of the tangent line" and if the graph is itself a line, it is its own "tangent line".)