Constants math problem

by gator
Tags: constants
 P: 16 Given a, b are constants and lim x approch 1, a root x+3 - b all over x-1 equals 1. Find a and b No clue how to answer this, but this is what I think i can do a) get rid of the sqrt b) apply limit See, the problem is I have to unknows so i dont know what to do
 P: 787 Is this your problem? $$\lim_{x\rightarrow{1}} \frac{a\sqrt{x+3}-b}{x-1}=1$$?
HW Helper
P: 2,954
 Quote by gator Given a, b are constants and lim x approch 1, a root x+3 - b all over x-1 equals 1. Find a and b No clue how to answer this, but this is what I think i can do a) get rid of the sqrt b) apply limit See, the problem is I have to unknows so i dont know what to do
If the version posted in LaTex is correct, note that the denominator goes to zero when x->1. For the quotient to have a finite limit, the numerator must also go to zero when x is set to 1.

You get a simple linear relationship between a and b. ---(1)

Now you can use L'Hopital's Rule to evaluate a limit of the form 0/0. So differentiate both numerator and denominator. You know that the quotient of these two is also going to be 1 at the limit x->1.

So set x = 1 in that. The b term would have vanished, so you can now solve for a. Put that back in equation (1) and work out b, you're done.

 Related Discussions Quantum Physics 1 Beyond the Standard Model 1 General Physics 10 Biology, Chemistry & Other Homework 2 General Physics 4