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Inverse Functions Practice Questions

Last Updated : 08 Aug, 2024
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Inverse functions are those functions which reverse the actions of another function and reversing its operation. It swaps input and output values, allowing for the retrieval of the original input from a given output.

This article consist of a series of Inverse Functions Practice Questions focused at strengthening your understanding and proficiency in this fundamental concept of Inverse functions.

What are Inverse functions

The inverse function is inverse of a function.

let f be a function then f−1 represents the inverse of function (f), such that:

f{f −1 (y)} = y for all y ∈ Range (f)

and

f−1{f(x)} = x for all x ∈ Domain(f)

  • Graph of an inverse function is a reflection of the original function across the line y = x.

If f(x) = log x then its inverse is, f-1(x) = ex and the graph for the same is added below:

logarithm-and-exponential-graph
Inverse Functions
  • To graph the inverse function, interchange the roles of x and y. If the original graph passes through (a, b), the inverse graph will pass through (b, a).

Inverse function of Some Common Functions

Inverse function of some common functions are added in the table below:

Function

Inverse Function

Domain of Function

Range of Inverse Function

f(x) = x+a

f−1(x) = x−a

All real numbers

All real numbers

f(x) = x-a

f−1(x) = x+a

All real numbers

All real numbers

f(x) = ax (a≠0)

f−1(x) = x/a

All real numbers

All real numbers

f(x) = x/a (a≠0)

f−1(x) = ax

All real numbers

All real numbers

f(x) = x2

f−1(x) = √x​

x ≥ 0

x ≥ 0

f(x) = √x​

f−1(x) = x2

x ≥ 0

x ≥ 0

f(x) = x3

f−1(x) = ∛x​

All real numbers

All real numbers

f(x) = ∛x

f−1(x) = x3

All real numbers

All real numbers

f(x) = ln(x)

f−1(x) = ex

x > 0

All real numbers

f(x) = ex

f−1(x) = ln(x)

All real numbers

x > 0

f(x) = sin(x)

f−1(x) = arcsin(x)

−π​/2 ≤ x ≤ π/2​

−1 ≤ x ≤ 1

f(x) = cos(x)

f−1(x) = arccos(x)

0 ≤ x ≤ π

−1≤ x ≤ 1

f(x) = tan(x)

f−1(x) = arctan(x)

−π​/2 < x < π/2​

All real numbers

Inverse Functions Practice Questions - Solved

1. Find the inverse of the function ?(?)=2?+3

Replace f(x) with y:

y = 2x + 3

Swap x and y: x = 2y + 3

Solve for y: y = (x-3)/2​

So, f−1(x) = (x-3)/2​

2. Determine the inverse of ?(?) = (?-4)/3

Replace f(x) with y:

y = 3x−4​

Swap x and y: x = (y-4)/3

Solve for y: y = 3x + 4

So, f-1(x) = 3x + 4

3. If f(x) = x2 for x ≥ 0, find f-1(x):

Replace f(x) with y:

y = x2

Swap x and y: x = y2

Solve for y: y = √x​

So, f-1(x) = √x​ for x ≥ 0

4. What is the inverse function of f(x)=tan⁡(x) -?/2<x<?/2.

Replace f(x) with y:

y = tan(x)

Swap x and y: x = tan(y)

Solve for y: y = arctan(x)

So, f−1(x) = arctan(x)

5. If f(x)=x 1/x​ for x≠0, find f-1(x)

Replace f(x) with y:

y = 1/x

Swap x and y: x=1/y

Solve for y: y= 1/x

So, f-1(x)= 1/x​

6. What is the inverse function of f(x) = x3

Replace f(x) with y:

y = x3

Swap x and y: x = y3

Solve for y: y = ∛x​

So, f-1(x) = ∛x​

7. Determine f-1(x) for the function f(x)=ex

Replace f(x) with y:

y = ex

Swap x and y: x = ey

Solve for y: y = ln(x)

So, f-1(x) = ln(x)

Inverse Functions Practice Questions - Unsolved

Q1. Find the inverse of the function f(x) = (x+2)/(3x-1)​.

Q2. Determine f-1(x) for the function f(x) = log(x).

Q3. If f(x) = arcsin (x), what is f-1(x)?

Q4. Given f(x) = arccos (x) for −1 ≤ x ≤ 1, find f-1(x).

Q5. What is the inverse function of f(x) = arctan(x)?


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