(∫_0^∞)(x^2) exp(-2 x)\[DifferentialD]x

(∫_0^∞)x exp(-2 x)\[DifferentialD]x

(∫_0^∞) exp(-2 x)\[DifferentialD]x

(∫_0^∞)((r^2 Sin[k r])/((E^((2 r Z)/(Subscript[a, 0]))) ))\[DifferentialD]r

Integrate[(u*Sin[u])/
   (E^((2*u*Z)/Subscript[a, 0]* k)*k), 
  {u, 0, Infinity}]

(∫_0^∞)(1/(((x+1))^4))\[DifferentialD]x

Integrate[ 1/((1+x)^4), x]

(∫_0^∞)((r^2 Cos[k r])/((E^((2 r Z)/(Subscript[a, 0]))) ))\[DifferentialD]r

(∫_0^∞)((r^2 Exp[i k r])/((E^((2 r Z)/(Subscript[a, 0]))) ))\[DifferentialD]r

-4 (Pi/k)(∫_0^∞)((r Sin[k r])/((E^((2 r Z)/(Subscript[a, 0]))) ))\[DifferentialD]r

FullSimplify[Integrate[ Exp[-2 A Sqrt[x^2 + y^2 + z^2] + I ( x (Subscript[k, x]) + y (Subscript[k, y]) + z (Subscript[k, z]))], {x, 0, Infinity}, {y, 0, Infinity}, {z, 0, Infinity}], A∉Reals && (Subscript[k, x])∉Reals && (Subscript[k, y])∉Reals && (Subscript[k, z])∉Reals]

FullSimplify[Integrate[ Exp[-2 A Sqrt[x^2 + y^2 + z^2] + I ( x a + y b + z c)], {x, 0, Infinity}, {y, 0, Infinity}, {z, 0, Infinity}], A∉Reals && a∉Reals && b∉Reals && c∉Reals]

Integrate[ Exp[-2 A Sqrt[x^2 + a^2] + I ( x (Subscript[k, x]) + b )], {x, 0, Infinity}]