6. Ja: 2dx (try x = 2u and factor out 4 from the denominator) 1 7. Ja (x 2)24 da (combine the ideas above; you're allowed to do two or more substitut tions in a row. Does order make a difference?) 8. So (x-2)2+4 da (use the ideas above) 9. So 12 1 dx (try x = tanh(u) where tanh = sinh / cosh is the hyperbolic tangent func- tion. The hyperbolic sine (sinh) and hyperbolic cosine (cosh) are defined at the end of these notes if you've forgotten their definitions.)