Hello, any assistance on the problem would be much appreciated. I have a vague idea but cant quite remember what to do.

(+1)! + (x+1)! =y^2 xx^2, how many pairs such thatyandxare a pair of positive, non-negative integers?y

Any help would be great, my maths tutor set this and i honestly cant quite remember what to do in this case.

Cheers