Trying to teach my daughter how to do this, i'm at a loss. i can't remember.

What is the prime factorization of 23 ?me with this question

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.