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View Full Version : If y= x-1 1/ (x-1), does y have a real between -2 and 2?


rorymckeague
Apr 16, 2012, 06:52 AM
If y = x - 1 + \frac{1}{(x - 1)}

show that y can't have a real value between -2 and 2?

ebaines
Apr 17, 2012, 05:43 AM
Suggest that you set up an equation that gives x as a function of y. Start by multiplying through by (x-1), rearrange, and you'll get a quadratic in x. Use the quadratic equation to solve for values of x given any y, and it will have a term that includes \sqrt{y^2-4} . So |y| can not be less than 2.

rorymckeague
Apr 17, 2012, 11:38 AM
Once again thank you for your help