This is a free lesson from our course in Algebra I
This lesson explains how to find a function's domain from its equation. If a function f is defined by an expression with variable x, then the domain
is the set of all real numbers that can be substituted for x such
that the resulting value of the function is a real number. E.g. if you've to find the domain of the function
f(x) = x + 3, you can see that there is no restriction on x
as all values of x as long as it is a real number, lead to a real number
for f(x). Hence, the domain of this function is the set of all real numbers.
Also, the set of all correspondence values of f(x) is called range.E.g. Find the domain of function f defined by
f (x) = 1 / ( x  1)
Solution:
x can take any real number except 1 since x = 1 would make the denominator equal to zero and the division by zero is not allowed. Hence the domain in interval notation is given by
( , 1) U (1 , +).
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