Question

For what value of x is the rational expression below undefined?

2x + 4
X -7
ОООО
c. 7
OD. 2

Answer 1

The value of x is 7 ⇒ answer c

Explanation:

* Lets explain how to solve the problem

- The rational expression has a numerator and a denominator

- Ex: f(x)/g(x) is a rational expression where f(x) is the numerator and

g(x) is the denominator

- The fraction is undefined if its denominator is 0

- If g(x) = 0 then the rational expression f(x)/g(x) is undefined

* Lets solve the problem

∵ The rational expression is
`(2x+4)/(x-7)`

∴ The numerator is 2x + 4

∴ The denominator is x - 7

- Put the denominator equal zero to find the value of x which makes

the denominator equal zero

∴ x - 7 = 0 ⇒ add 7 to both sides

∴ x = 7

* The value of x is 7