Answer:
No, they are not necessarily steeper.
Step-by-step explanation:
Steepness is the <em>absolute value</em> of a slope. (The sign of a slope determines the direction of the incline: negative slope corresponds to pointing up to the left, positive slope points up to the right.)
So it is only the absolute value of a slope that should be used in any comparison. Because of that, one cannot, in general, say that negative slopes are steeper than positive slopes.