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Comment on 2x over y
Why do we have (y -ve for
The problem with that
The problem with that approach (multiplying both sides by y) is that we don't know whether y is positive or negative.
If y is negative, we must reverse the inequality sign. If y is positive, the direction of the inequality sign stays the same.
For more see https://www.gmatprepnow.com/module/gmat-algebra-and-equation-solving/vid...
So is it safe to say you
That's correct. Having or not
That's correct. Having or not having a negative symbol in front of a variable doesn't tell us anything about whether that variable is positive or negative.
For example, x can be negative or positive.
Likewise, -x can be negative or positive.
then in the second case how
While rewriting the
While rewriting the inequality in statement 2, we are able to avoid multiplying or dividing both sides of the inequality by a variable. So, in the end, we can be certain that y is greater than zero.
If in above problem assume it
IF we had been able to
IF we had been able to conclude (from statement 2) that y is negative, then the answer would be E.
From statement 1, we learned that, if y is negative, then x < 5
So, when we combine the two statements, we can conclude that x < 5
The target question asks "Is x negative?"
So, if x < 5, then x COULD equal 4, which means x IS positive.
Conversely, if x < 5, then x COULD equal -1, which means x is NOT positive.
Since we cannot answer the target question with certainty, the combined statements are not sufficient.
Brilliant explanation in
Great question, I completely
You're not alone. Many
You're not alone. Many students will forget that y can be either positive or negative.
Great video Brent. If using a
Think I get it now Brent to
That's correct.
That's correct.
The target question, "Is x > 0?" contains no given information.
So, if we know that x > 5, then we can be certain that x > 0.
In other words, the answer to the target question is a definite YES (x IS greater than 0), which means the statement is sufficient.
Brilliant thanks Brent for