SOLUTION: The GCF of 15y +20 is 5. The GCF of 15y + 21 is 3. Find the GCF of the product (15y+20)(15y + 21). Thank you for your help in solving this problem. Daniel H. Jack

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Question 1015177: The GCF of 15y +20 is 5. The GCF of 15y + 21 is 3. Find the GCF of the product (15y+20)(15y + 21).
Thank you for your help in solving this problem.
Daniel H. Jack
Found 3 solutions by rothauserc, ikleyn, MathTherapy:
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website!
15y+20 = 5(3y+4)
15y+21 = 3(5y+7)
:
(15y+20)(15y+21) = 5(3y+4)3(5y+7) =
15(3y+4)(5y+7) =
15(15y^2 +41y +28) =
225y^2 +615y +420
:
(15y+20)(15y+21) = 225y^2 +615y +420
:
therefore 15 is the GCF

Answer by ikleyn(52909)   (Show Source):
You can put this solution on YOUR website!
.
For your information:

Actually, the greatest common factor, or GCF, is the greatest factor that divides two numbers.

By considering ONE number, one value 5y +20, it is NONSENCE to use the term GCF.
It is applicable when you consider at least two numbers.
It is NOT APPLICABLE when you consider one number.

Answer by MathTherapy(10557)   (Show Source):
You can put this solution on YOUR website!

The GCF of 15y +20 is 5. The GCF of 15y + 21 is 3. Find the GCF of the product (15y+20)(15y + 21).
Thank you for your help in solving this problem.
Daniel H. Jack

Simply multiply the 2 GCFs to get 5(3), or