For positive integers x and z, which of the following can be written as z^2? Choose the correct choice
A) x^2+1  B) x^2-1  C) x^2-24  D) x^2+11  E) x^2-11
Plug values: if x=6, then 6^2-11=25   The question asks which of the following CAN be written as z^2. If x=6, then x^2-11 CAN be written as 5^2.   Answer: x^2+11
<result>D</result>
For positive integers x and z, which of the following can be written as z^2?