sandy wrote:
If \(41\) is a factor of positive integer \(y\), which of the following MUST be divisible by \(y\)?
Indicate all possible values.
A. \(82y+82\)
B. \(41y\)
C. \(41+y\)
D. \(y/41\)
If 41 is a factor of y, we can also say that
y is a multiply of 41Or we could say that
y = 41k for some integer k
Now let's check each answer choice....
A. 82y + 82 = 82(
41k) + 82
Is 82(
41k) + 82 divisible by
41k? NO.
We know that 82(
41k) is divisible by
41k, but it need not be the case that 82 is divisible by
41kFor example, if k = 3, then y = 41(3) = 123, and 82 is NOT divisible by 123
OR, here's another way to put it.
If 41 is a factor of y, then y COULD equal 123.
This means 82y + 82 = 82(123) + 82 = 10,168 and 10,168 is NOT divisible by 123
Statement A need not be trueB. 41y = (41)(
41k)
Is (41)(
41k) divisible by
41k?
YES
41k divides into (41)(
41k) 41 times
Statement B IS trueC. 41 + y = 41 +
41kIs 41 +
41k divisible by
41k?
NO.
For example, if k = 3, then we can ask: Is 41 + 41(3) divisible by 41(3)?
Simplify to get : Is 164 divisible by 123?
NO.
Statement C need not be trueD. y/41 =
41k/41 = k
Is k divisible by
41k?
NO.
If k = 3, then 3 is not divisible by 41(3)
Statement DC need not be trueAnswer: B
Cheers,
Brent