Question

Using the GCF you found in Part B, rewrite 72 + 81 as two factors. One factor is the GCF and the other is the sum of two numbers that do not have a common factor. Show your work. (4 points)

Answer 1

$72|2\\36|2\\18|2\\.\ 9|3\\.\ 3|3\\.\ 1|\\\\72=2\cdot2\cdot2\cdot\boxed{3}\cdot\boxed{3}\\\\81|3\\27|3\\.\ 9|3\\.\ 3|3\\.\ 1|\\\\81=\boxed{3}\cdot\boxed{3}\cdot3\cdot3\\\\GCF(72,\ 81)=\boxed{3}\cdot\boxed{3}=9\\\\72=9\cdot8\\81=9\cdot9\\\\\boxed{72+81=9(8+9)}$