Engineer1 wrote:
Bunuel wrote:
Tough and Tricky questions:Inequalities.
If x and y are integers and xy does not equal 0, is xy < 0?
(1)\( y = x^4 –x^3\)
(2)\( -12y^2 – y^2x + x^2y^2 >0\)
Bunuel KarishmaB
Statement 1:\( y = x^4 –x^3\)
This equation is insufficient to be solved by itself. We would need at least two equations. Plus, we cannot look to solve for XY without increasing the power of X further. Is plugging in a number even necessary? I want to understand a more logical way (without getting bogged down by 4th power of x) to deem stmt 1 Insufficient.
I spent time on statement 1 and later decided this is insufficient for above reason. Thanks for yourresponse.
Question: Is xy < 0?
which means 'Is xy negative?' which means do they have opposite signs or same signs? (They can't be 0).
(1)\( y = x^4 –x^3\)
Easy to give them same signs. For all numbers greater than 1 on the number line, x^4 > x^3. So if x is greater than 1, both x and y are positive.
For opposite signs, I want x to be positive
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Statistics : Posted by KarishmaB • on 15 Oct 2014, 16:49 • Replies 10 • Views 12305
