First find the inverse function:
y = -x^2 + 2
y - 2 = -x^2
2 - y = x^2
x = (2 - y)^0.5
Therefore inverse: y = (2 - x)^0.5 [x < 2]
Then simply sub in four random values for x to give your answer (hint, for your x values, use 1, - 2, - 7 and - 14. These should yield nice integer values for y)