Date: 8/2/96 at 1:58:23 From: Alfred T Chu Subject: Inverse Function Dear Dr. Math, I have a questions: z(x) = 4x + 15. How do I find the inverse function of z(x)? Sincerely, Alfred
Date: 8/6/96 at 10:56:53 From: Doctor Jerry Subject: Re: Inverse Function Dear Alfred, You want the inverse function of z(x) = 4x+15. Usually, in inverse function questions, it is important to specify the domain of the function. For the function z, I assume the domain is R, the set of all real numbers. The function z gives y = z(x) values when x values are given. The function zinv gives x values when y values are given. So, suppose y = z(x) is given. What value of x is required for this? To determine x, we solve the equation y = 4x+5 for x. I feel certain you can do this. I find x = (y-5)/4. So z inv(y) = (y-5)/4. Some persons prefer the variable of a function to be x, so they prefer to write zinv(x) = (x-5)/4 when describing the function zinv to another person. -Doctor Jerry, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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