Hello,
I came across this Data Sufficiency problem that was posted here sometime ago:
Is a > 0?
1. a^3 - a < 0
2. 1 - a^2 > 0
The OA is C
My approach is as follows:
1) a^3 - a < 0
=> a^3 < a
If a = -2 then, -8 < -2 - True
If a = 1 then, 1 < 1 - False
In-sufficient
2) 1 - a^2 > 0
=> (1+a)(1-a) > 0
(1+a) > 0 and (1-a) > 0
or
(1+a) < 0 and (1-a) < 0
=> a > -1 and a < 1
or a < -1 and 1 < a
=> 1 > a > -1
or 1 < a < -1
In-sufficient
I am not sure how to proceed further from this point onwards by combining both. Can you please assist? Thanks a lot.
Best Regards,
Sri
I came across this Data Sufficiency problem that was posted here sometime ago:
Is a > 0?
1. a^3 - a < 0
2. 1 - a^2 > 0
The OA is C
My approach is as follows:
1) a^3 - a < 0
=> a^3 < a
If a = -2 then, -8 < -2 - True
If a = 1 then, 1 < 1 - False
In-sufficient
2) 1 - a^2 > 0
=> (1+a)(1-a) > 0
(1+a) > 0 and (1-a) > 0
or
(1+a) < 0 and (1-a) < 0
=> a > -1 and a < 1
or a < -1 and 1 < a
=> 1 > a > -1
or 1 < a < -1
In-sufficient
I am not sure how to proceed further from this point onwards by combining both. Can you please assist? Thanks a lot.
Best Regards,
Sri
