Question 944573
Try examining the two sides of 30 and 40.


One of these will give an integer for x.

{{{30^2+40^4=x^2}}}, {{{x^2+30^2=40^2}}}, {{{x^2+40^2=30^2}}}.


x=50, x=26.458, x=sqrt(900-1600);
Only the x=50 will work.  The other two is noninteger or imaginary.
{{{highlight(x=50)}}} with 30 and 40.