Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

when x<0, |x| = -x...so the first eq becomes Y = -x + (-x) = -2x ?????

When x is negative, you don't replace x with -x; if x is negative, then -x is a positive number. If x is negative, there is a negative sign 'inside' of x.

Now, if x is negative, you can replace |x| with -x, because if x is negative, -x will produce the 'positive equivalent' of x. _________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

But thanks Ian for this last bit. It made me see |x| in a different light. Never thought you could write |x| as -x when x is negative. Makes perfect sense.