Question 156950
First factor the two expressions:



{{{r^2 + 16r + 64=(r+8)(r+8)}}}



{{{r^2 + 8r=r(r+8)}}}



Now collect the unique factors (and the factors that occur most) to get {{{r(r+8)(r+8)}}} (note: the last two factors came from the first expression). So the LCM is {{{r(r+8)(r+8)}}}