Find the domain of f(x) = x2 - 2x-8 / x2 - 2x- 35
- Thread starter RicanGurl
- Start date
f(x) = x2 - 2x-8 / x2 - 2x- 35
Not quite sure what is meant.
x^2 - 2x-8 / x^2 - 2x- 35 means \(\displaystyle x^2-2x-\frac{8}{x^2}-2x-35\)
Are you after ( x^2 - 2x-8) / (x^2 - 2x- 35) which is \(\displaystyle \frac{x^2-2x-8}{x^2-2x-35}\) or something else?
Not quite sure what is meant.
x^2 - 2x-8 / x^2 - 2x- 35 means \(\displaystyle x^2-2x-\frac{8}{x^2}-2x-35\)
Are you after ( x^2 - 2x-8) / (x^2 - 2x- 35) which is \(\displaystyle \frac{x^2-2x-8}{x^2-2x-35}\) or something else?
Re: i dont know how
Factor the numerator and denominator, cancel any like terms. After simplification, if there is any you will set your two factored binomials of the denominator equal to zero and solve for x.... you do know how to factor a trinomial, right?
RicanGurl said:
Factor the numerator and denominator, cancel any like terms. After simplification, if there is any you will set your two factored binomials of the denominator equal to zero and solve for x.... you do know how to factor a trinomial, right?
Re: Uhm
You could either factor the denominator using a method like grouping, or you could complete the square (quadratic formula) to find your zeros. You want to find all numbers x such that f(x) = 0.
http://www.purplemath.com/modules/factquad2.htm
http://www.purplemath.com/modules/sqrquad.htm
Ask your teacher to go over one of the above with you, which ever one is more familiar, as of now.
RicanGurl said:
You could either factor the denominator using a method like grouping, or you could complete the square (quadratic formula) to find your zeros. You want to find all numbers x such that f(x) = 0.
http://www.purplemath.com/modules/factquad2.htm
http://www.purplemath.com/modules/sqrquad.htm
Ask your teacher to go over one of the above with you, which ever one is more familiar, as of now.
The denominator of a fraction can't be zero. So, set the denominator equal to 0:
x<SUP>2</SUP> - 2x - 35 = 0
Factor the left side:
(x - 7)(x + 5) = 0
Now, if the product of two factors is 0, at least one of the factors must be equal to 0.
Either (x - 7) = 0, or (x + 5) = 0
If x - 7 = 0, x = 7. If x + 5 = 0, x = -5.
So, we cannot include 7 or -5 in the domain, because those values would cause the denominator to be 0.
The domain is all real numbers except 7 and -5.
x<SUP>2</SUP> - 2x - 35 = 0
Factor the left side:
(x - 7)(x + 5) = 0
Now, if the product of two factors is 0, at least one of the factors must be equal to 0.
Either (x - 7) = 0, or (x + 5) = 0
If x - 7 = 0, x = 7. If x + 5 = 0, x = -5.
So, we cannot include 7 or -5 in the domain, because those values would cause the denominator to be 0.
The domain is all real numbers except 7 and -5.