so, what you need to do here is factor one thing out--pick something that both terms have in common. in this case, the thing in common is the variable r.
factor out an r. your result is:
r(2r + 1)
the 1 comes from the "implied" or "understood" default coefficient that comes before every variable. the coefficient is 1 if a variable is standing alone (like if a problem just says "x")
