also, note that, if you want, you could go in the opposite direction: you could factor these expressions further before tackling the problem.
for instance, you could factor statement (2) into
(x - 1)(x + 1) < 0
from which you'd deduce that x + 1 is positive and x - 1 is negative (because that's the only way the product can be negative). this translates to -1 < x < 1.
INSUFFICIENT, because both positive and negative numbers are contained in this interval.
same sort of logic applies to statement (1) as well:
(x^3)(1 - x)(1 + x) < 0
set out a number line showing the 'solutions' of this inequality (i.e., the numbers that would be its solutions if it were an equation instead of an inequality): -1, 0, and 1. then, test the four resulting regions to see if they work in the inequality:
x < -1: doesn't work
-1 < x < 0: works
0 < x < 1: doesn't work
1 < x: works
INSUFFICIENT, because x can be negative (-1 < x < 0) or positive (1 < x).
if you take the two statements together, the only interval that satisfies both is -1 < x < 0
SUFFICIENT
answer = c
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
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