
Carl K. answered 09/02/19
Assistant Professor of Family Medicine
The factors of 36 are 2,2,3,3 and 45 is 3,3,5
The greatest common factor is the product of all of the factors common to both.
3 is common, and found twice in each, so we use the product, 3 x 3 or 9
Using the distribution rule ab + ac = a(b + c)
We can say 36 + 45 is also 2x2x3x3 + 3x3x5
Removing the common factors, 3 and 3 or the GCF 9 we have:
3x3(2x2) + 3x3(5) or 9(2x2) + 9(5) (Read this as 3 times 3 times 2 times 2 plus 3 times 3 times 5)
9(4) + 9(5) (nine times four plus nine times five)
By the distribution property, 9(4+5) [Is the same as nine times (four plus five)]