How do you determine if a function is one-to-one?
If the set of inputs have a single output every time, then it is said to be a function. Every function has a domain and a range.
Answer: Horizontal line testing and algebraic testing are two ways to determine a one-to-one function.
See detailed Explanation.
A domain is the set of inputs or possible values of x for a function f(x), to make the equation true.
A range is the set of outputs/solutions for the given output for the function f(x) or y.
One To One functions are the functions that have a unique value of 'x' for every 'y'.
For example: Let the function (x + 3) be the a one-to-one function. Therefore f(x) = y
To determine that whether the function f(x) is a One to One function or not, we have two tests.
1) Horizontal Line testing: If the graph of f(x) passes through a unique value of y every time, then the function is said to be one to one function.
For example Let f(x) = x3 + 1 and g(x) = x2 - 1
In the above graphs, the function f (x) has only one value for y and is unique, whereas the function g(x) doesn't have one-to-one correspondence.
For function g(x), the graph is passing through two ordered pairs. So, it doesn't have a unique y for every x. Therefore, g(x) is not a one-to-one function.
2) Algebraic Testing: The function is said to be one to one if a = b for every f(a) = f(b)
Let, f(x) = 5x3 - 1,
f(a) = f(b)
⇒ 5a3 - 1 = 5b3 - 1
⇒ 5a3 = 5b3
⇒ a3 = b3
⇒ ∛ a3 = ∛ b3
⇒ a = b
So, the function f(x) = 5x3 - 1 is one-to-one.