let f(x) =∫_0 ^(+∞) (dt/(t^4 +x^4 )) with x>0
1) determine a explicit form of f(x)
2) find also g(x) =∫_0 ^∞ (dt/((t^4 +x^4 )^2 ))
3)give f^((n)) (x) at form of integral
4) calculate ∫_0 ^∞ (dt/(t^4 +8)) and ∫_0 ^∞ (dt/((t^4 +8)^2 ))
5) calculate A_n =∫_0 ^∞ (dt/((t^4 +x^4 )^n )) with n integr natural