we have to prove x^5+x^3>2x^4---1
now if X <=0 relation 1 will not hold true.Hence condition 2 is not sufficient
from 1 we get (x-1)>0
or (x-1)^2>0
or (x^2-2x+1)>0
or (x^2+1)>2x
or x^3(x^2+1)>2x^4..since x is positive multiplying both sides by x^3
or x^5-x^4>x^4-x^3...sufficient
Ans option A
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19) Inequality DS
Source: Beat The GMAT — Data Sufficiency |
since 1st statement is X>1 -- The question then can be reduced to X>1 (since X is positive we can divide) --- which is statement 1.
Hence A.
Is that the correct approach?
Hence A.
Is that the correct approach?
correct approach
x^4(x-1)>x^3(x-1)
x^4(x-1)-x^3(x-1)>0
(x-1)(x^4-x^3)
x^3(x-1)^2>0.......correct
x^4(x-1)>x^3(x-1)
x^4(x-1)-x^3(x-1)>0
(x-1)(x^4-x^3)
x^3(x-1)^2>0.......correct
Is X^5-X^4>X^4-X^3?
1. X>1
2. X is integer
My take on this q
x^4(x-1) > x ^3(x-1)
or simply say x^4>x^3 ...rephrase it as is X +ve ?
Statement A - x >1 x + ve
Statement B x can be +ve or -ve
Answer A
Please let me know if this make sense
1. X>1
2. X is integer
My take on this q
x^4(x-1) > x ^3(x-1)
or simply say x^4>x^3 ...rephrase it as is X +ve ?
Statement A - x >1 x + ve
Statement B x can be +ve or -ve
Answer A
Please let me know if this make sense
