1967 AMC 12 Question 7
AMC12 · 1967 AMC 12
If $\dfrac ab\lt-\dfrac cd,$ where $a,$ $b,$ $c,$ $d$ are real numbers and $bd\ne0,$ then:
$a$ must be negative
$a$ must be positive
$a$ must not be zero
$a$ can be negative or zero, but not positive
$a$ can be positive, negative, or zero