Question

What number can you multiply by √7 to get a rational number? (select each correct answer.)

Answer 1

Answers: Choice A, choice B, and choice C

Those two values, when multiplied by the given value, will lead to a rational number. If you pick choice A, then you get 7 as a result after multiplying. If you choose choice B, then you get -7

Note that
7 = 7/1
-7 = -7/1
So 7 and -7 are rational

Also, when multiplying 0 by any number, the result is always 0. The rule is 0*x = x*0 = 0
The value 0 is rational as 0 = 0/1

The only non-answer is choice D as 7*sqrt(7) can't be expressed as a ratio of two whole numbers.

Answer 2

A) √7 is the only option.