7. To evaluate the integral S 2x sin(3x) dx using Integration By Parts, write down the simplified integral after using S udv = uv - fvdu. 2x a 3 cos(3x) - S 2 cos(3x) dx c) 6x cos(3x) - S 6 sin(3x) dx b) 2x cos(3x) + = S cos(3x) dx d) - - sin(3x) + ~ f cos(3x) dx e) Others 8. To evaluate the integral S dx V81-x2 using trigonometric substitution, find an appropriate trig substitution and write down the simplified new integral. Formulas: x = a sin 0 for Va2 - x2, x = asec0 for Vx2 - a2 , x = atan0 for Vaz + x2. a) x = 9 sin 0, Sde c) x = 9 sec 0 , S seco de b) x = 9tan0, Scos2 0 de de d) x = 9 sin 0 , S e) Others 9 cos 8