Thursday
April 2, 2015

Homework Help: Algebra-I'm still stuck

Posted by Rachal on Thursday, February 3, 2011 at 4:38am.

The one-to-one function f is defined by f(x)=(4x-1)/(x+7).

Find f^-1, the inverse of f. Then, give the domain and range of f^-1 using interval notation.

f^-1(x)=
Domain (f^-1)=
Range (f^-1)=

Any help is greatly appreciated.



Algebra - helper, Wednesday, February 2, 2011 at 7:05pm
f(x)=(4x-1)/(x+7)
y = (4x-1)/(x+7)

Rewrite as:
y = (4x)/(x+7)- 1/(x+7)
Multiply both sides by x+7:
(x + 7)y = 4x - 1
Expand out terms of the left hand side:
xy + 7y = 4x - 1
xy - 4x = -7y - 1
x(y - 4) = -7y - 1
Divide both sides by y - 4:
x = (-7y - 1)/(y - 4)

f^-1 = (-7x - 1)/(x - 4)

Can you do the domain and range now?




Algebra - Rachal, Wednesday, February 2, 2011 at 7:11pm
I don't know if this is right but this is what I came up with.

f^-1=(-7x+1)/(x-4)
domain f(^-1)=(-inf,-7)U(-7,inf)
range f(^-1)=(-inf,4)U(4,inf)

Let me know if it looks right. Thanks





Math - inverse - MathMate, Thursday, February 3, 2011 at 12:11am
The domain and range suggested apply to f(x). You will see that the vertical asymptote is at x=-7 when the denominator becomes zero.

f(x)=(4x-1)/(x+7)
domain f(^-1)=(-inf,-7)U(-7,inf)
range f(^-1)=(-inf,4)U(4,inf)

The domain and range of f-1(x) is equal to the range and domain respectively of f(x). Double check by evaluating the denominator at the singular points.

Post again if you need confirmation.

I'm still not getting it

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Algebra - Ok I got another one I can figure out The one-to-one function f is ...
Algebra- is my answer right - The one-to-one function f is defined by f(x)=(4x-1...
algebra - Graph the following function using the technique of shifting, ...
Trigonometry - In this problem, you will describe in detail how we arrive at the...
Advanced Algebra - What is the inverse of each of the functions defined by the ...
algebra - 1 (a) A function passes through the points (0, -5), (1, 0), (2, 7). ...
graphing - (0,-2)is the vertex- what is the domain and range??? State the domain...
Math - HELP PLEASE!!! I'm having some trouble with this question on my Maths hw...
precalculus check immediately - suppoe f is a function with domain [1,3]and ...
Pre-calculus - Given the following values for f(t): t : f(t) 3 : -7 6 : 6 9 : 19...

Members