Question

the expression \[\sqrt{x^2-9}\] is a real and irrational number when x is equal to?

a -3
b 0
c 5
d 4

Answer 1

For the expression to give you a real number, \(x^2>9\). That eliminates the first two choices. What is the value of the expression for the other two choices?

Answer 2

5^2-9 = 16
4^2-9 = 7