Answer:
All of them are true.
Step-by-step explanation:
x^2 y - z / x^2 is true. x^2, when divided by itself, cancels itself out, so the equation that is left is y - z.
For the second one, a/c + b/c is true because when you add a + b = it will change; it will be added together. the remaining c will stay the same, as it is the denominator/the same, so you keep it as it is.
For the final one, you distribute ^2 to (a+b), so they become a^2 + b^2.
This means that all of the statements are true.