Integrate e^[a*sqrt(b^2+x^2)] * e^c*x I can integrate the first part alone, i.e. ∫ea*√(b2+x2) and the result is [√(b2+x2)/a - 1/a2] ea*√(b2+x2). For the full integral, i.e. ∫ea*√(b2+x2) * ec*x I tried using integration by parts but it does not work since the exponent of the first e is not simply x. the second exponent was originally a cos but that is still much harder. Any ideas?