VeritasPrepKarishma wrote:
Archit143 wrote:
Need Help!!! Urgent
What is the difference between the solution of below problems, Is there any difference in the approach:-
1. X^3 > X
soln: -1<X<0 or X>1
If we follow the above principle for solving than the answer to below equation must be:
2. a^3< a^2 + 2a
-1<a<0 or a>2
but the answer as per MGMAt quant book is
0<a<2 or a<-1
Pls help me in getting the right concept.........
Responding to a pm:
2. a^3< a^2 + 2a
a^3 - a^2 - 2a < 0
a(a - 2)(a + 1) < 0
......-1.....0............2.......
Since you want the expression to be negative, the required range is a < -1 or 0 < a < 2 (Notice the sign in the original inequality. It is less than)
The range you have written: -1<a<0 or a>2 is for the expression to be positive.
Check out these posts for further clarification:
http://www.veritasprep.com/blog/2012/06 ... e-factors/http://www.veritasprep.com/blog/2012/07 ... ns-part-i/http://www.veritasprep.com/blog/2012/07 ... s-part-ii/http://www.veritasprep.com/blog/2012/07 ... qualities/Karishma
You are no less than Ron ...I would rate you above them in Maths
I mean what great explanations.......
can you fw the links of your blog on MODULUS, various type of questions.....
Thanks a trillion....I am sure i have added atleast 1 point to my maths score.......
Was it so simple!!!!!!!!I am thinking now!!!!!!!!!!!!!!!!!!!!
Waiting for links on modulus!!!!!!!!!!!!!
Archit
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