Question

Which must be true in order for the relationship to be correct?


and
and
and

Answer 1

I can’t see the relationship or the answer choices — it looks like part of your question got lost. Could you paste the full problem (the relationship and the four statements) exactly as given?

Meanwhile, here are the common rules you’re probably being asked about (so one of these may be the intended answer):

- If the relationship is a/b = c/d (fractions equal), then the necessary and sufficient condition is ad = bc (cross-multiply).
- If the relationship is a/b < c/d and b and d are both positive, then ad < bc. If b and d are both negative the same rule holds (because both negatives cancel). If exactly one denominator is negative, you must reverse the inequality when you cross-multiply.
- If the relationship is a/b > c/d the signs are handled the same way as for "<": with positive denominators ad > bc; if one denominator is negative the inequality reverses.
- If any denominator could be zero you must also require the denominators be nonzero.

Paste the exact relation and the four choices and I’ll pick which must be true.