find the domain:
1/(x^2+2x-3)=square root of x
the denominator cannot be zero,
so x^2 + 2x-3 = (x+3)(x-1)
so x ≠ -3 or x ≠ 1
also in √x , x ≥ 0
so the domain would be the set of real numbers such that
x ≥ 0, x ≠-3, 1
I leave it up to you to write that in the notation that was taught to you.