Given a<b<c and c^4 < b^4 < a^4
From c^4 < b^4 < a^4
, since even powers are involved, this implies ∣c∣<∣b∣<∣a∣.
We need to find if there are values of a,b,c that satisfy both conditions for each statement.
Possible Scenarios for a,b,c:
All negative: a<b<c<0.
Example: a=−3,b=−2,c=−1.
Check conditions:
a<b<c⟹−3<−2<−1 (True)
∣c∣<∣b∣<∣a∣⟹∣−1∣<∣−2∣<∣−3∣⟹1<2<3 (True)
c^4 < b^4 < a^4
⟹(−1)^4 < (−2)^4 < (−3)^4
⟹1<16<81 (True)
This scenario is possible.
a,b negative, c positive: a<b<0<c.
However, we also need ∣c∣<∣b∣. This means c must be a positive number smaller than the absolute value of b.
Example: a=−3,b=−2,c=1.
Check conditions:
a<b<c⟹−3<−2<1 (True)
∣c∣<∣b∣<∣a∣⟹∣1∣<∣−2∣<∣−3∣⟹1<2<3 (True)
c^4 < b^4 < a^4
⟹(1)^4 < (−2)^4 < (−3)^4
⟹1<16<81 (True)
This scenario is possible.
c=0: If c=0, then a<b<0.
Check conditions:
a<b<c⟹a<b<0 (e.g., a=−2,b=−1,c=0) (True)
∣c∣<∣b∣<∣a∣⟹∣0∣<∣−1∣<∣−2∣⟹0<1<2 (True)
c^4 < b^4 <a^4
⟹0^4 <(−1)^4 <(−2)^4
⟹0<1<16 (True)
This scenario is possible.
Now let's evaluate each statement:
I. abc>0
This would be true if there's an even number of negative values.
In Scenario 2 (a=−3,b=−2,c=1), abc=(−3)(−2)(1)=6>0.
Therefore, I could be true.
II. a^3 * b^5 * c^7 <0
The sign of an odd power is the same as the sign of the base. So, this statement has the same sign as abc.
This means a^3 * b^5 * c^7 <0 if abc<0.
In Scenario 1 (a=−3,b=−2,c=−1), abc=(−3)(−2)(−1)=−6<0.
Therefore, a^3 * b^5 * c^7 = (−3)^3 * (−2)^5 * (−1)^7 =(−27)(−32)(−1)=−864<0.
Therefore, II could be true.
III. a^2 * b^4 * c^6 =0
For this expression to be 0, at least one of a,b,c must be 0.
In Scenario 3 (a=−2,b=−1,c=0), a^2 * b^4 * c^6 = (−2)^2 * (−1)^4 *(0)^6 =4×1×0=0.
Therefore, III could be true.
Since I, II, and III all have possible scenarios where they could be true, all of them could be true.
Answer is E