Domain of a Function
Date: 9/13/96 at 2:24:1 From: Bill Spoth Subject: Function Analysis Dr. Math, I need help. Let f be the function given by f(x)= x/sqrt(x^2 - 4). What is the domain of f(x)? Thanks, Dr. Math! Sincerely, Troubled Math Student
Date: 9/13/96 at 9:15:16 From: Doctor Leigh Subject: Re: Function Analysis Thank you for your question. To find the domain of any function you look for areas where the function is undefined. This normally includes negatives under radicals and zeros in the denominator of a fraction. Here we would have a zero in the denominator if x^2-4 = 0. We then solve for x and see that if x is either positive or negative 2 the function will be undefined. We are also dealing with a radical. To get a negative under the radical sign we set x^2-4 < 0. Solve the equation for x and you get x < 2, x > -2. So the domain of this function is negative infinity to -2 (non-inclusive) and 2 to infinity (non-inclusive) -Doctor Leigh Ann, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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