Answer:
+5 or -5.
Step-by-step explanation:
Given equation,
5x-10/x^2-25
When you divide something with zero, it becomes undefined. So, to be undefined, x will have to be that value which makes the divisor zero.
Now, x^2-25= 0
Or, x^2= 25
Or, x= +5,-5.
So, for the value +5 and -5, the divisor becomes zero and makes the whole equation undefined.