Calc question with area of region under graph?

The question I have is "Find the area of the region under the graph of the function f(x)=1/x^2 dx on the interval [1,4]. I'm at the part where its [x^-1/-1] with 4 at the top right outside and 1 at the bottom right outside. The next step equals [-1/x] with 4 at the top right outside and 1 at the bottom right outside. this sounds soo stupid but how did we go from [x^-1/-1] to [-1/x]?