Factor Tree?

[justskye]

okay i havent actually taken algebra since 8th grade so i forgot all the basics! i con not remember/figure out how to do a proper factor tree

one im stuck on is

40 , 20 , 4

i believe you have to find the GCF and i can not remember how to do this! please explain!

 

[HallsofIvy]

okay i havent actually taken algebra since 8th grade so i forgot all the basics! i con not remember/figure out how to do a proper factor tree

one im stuck on is

40 , 20 , 4

i believe you have to find the GCF and i can not remember how to do this! please explain!

This isn't a problem in "algebra", it is a problem in integer arithmetic. You should be able to look at "40" and immediately think "4*10"- and then "4= 2*2" and "10=2*5". So "40= 2*2*2*5". Similarly, "20= 2*10= 2*2*5". So your three given numbers are 2*2*2*5, 2*2*5, and 2*2. Now what is the largest number that is contained in all three?

 

[Bob Brown MSEE]

okay i havent actually taken algebra since 8th grade so i forgot all the basics! i con not remember/figure out how to do a proper factor tree

one im stuck on is

40 , 20 , 4

i believe you have to find the GCF and i can not remember how to do this! please explain!

You can find a GFC without completely factoring.

Just find ANY number that can be written as a factor, hear is how...

List: 40, 20, 4
obviously 2 can divide into each
List: (2)20, (2)10, (2)2
again 2 can divide into each
List: (2)(2)10, (2)(2)5, (2)(2)1
Nothing divides into 1, so we are done!