500 Math Flash Cards - #10

[meghanmhart]

I am working on question #10 - I don't understand why answer choice E - 42 is definitely not a factor of x squared?

[tommywallach]

Hey Meghan,

Could you post the question? Thanks!

-t

[meghanmhart]

x is divisible by 42. Which of the following numbers is definitely a factor of x squared? Choose all that apply.

a - 63
b - 33
c - 36
d - 8
e - 42

The answer listed is A and C and I am confused why it doesn't include E.

[tommywallach]

Hey Meghan,

That's definitely a typo if you've written it correctly. You're absolutely right that any multiple of 42 will still be a multiple of 42 when squared! I'll check on this!

-t

[esledge]

Hi Meghan and Tommy. I'm looking at the card right now. That 42 with factor tree is actually not a choice [E]; it is there as a reference for the "x is divisible by 42" constraint. That's why it is boxed in, differently than the choices [A] - [D]. But you are right, if that were choice [E], it would have been correct!