What does it mean through algebra

What is the common difference in the following arithmetic sequence 7,3,-1,-5

In the diagram below? p is circumscribed about quadrilateral abcd. what is the value of x

For the quadratic function [tex]y=(x+4)^2-1[/tex] , do the following: a) rewrite the function in the standard form, b) rewrite the function in intercept form, c) find the vertex, d) find the y-intercept, e) find the x-intercepts.