Hi lheiannie07,
Start off by identifying the question type:
Yes or no
We are given no information about a in the prompt, so it could be ANY number.
Let's check fact 1:
$$\left(1+a\right)^3\ is\ negative,\ so\ \left(1+a\right)^3\ <\ 0$$
As a rule, we know that if a cubed number is negative, its cubic root must also be negative, therefore:
$$\left(1+a\right)\ <\ 0$$
Subtracting 1 from both sides of the inequality yields:
$$a<-1$$
Therefore, a is always negative. Fact 1 is sufficient so we can slash answer choices B,C, and E
Now, to check fact 2:
$$\left(1-a\right)\ is\ positive,\ hence\ 1-a>0$$
Add an "a" to each side of the inequality and we will get:
$$1>a$$
Since the prompt doesn't give us any information regarding a, it could be anything, including decimals and zeros. As such, fact 2 is insufficient since it includes non-negative numbers (zero and positive decimals).
Answer choice A.
