restricted value

Question

how do you find the restricted value of x in the expression 9 over x²-5x

Answer 1

For a rational expression like

The basic issue is that a denominator cannot be zero. Dividing by zero is undefined in math. So, to find out what the issues are, purposely set the denominator equal to zero to see where the problems are.

So:

x² - 5x = 0

x(x - 5) = 0

This will be true if either element of this multiplication is equal to zero. So

x = 0 and x - 5 = 0

the second portion (x - 5 = 0) is true when x = 5.

So the "restricted" vales of x are x = 0 and x = 5.