Definate integrals

white_hype · New Member Offline Joined: 18 Sep 2005 Posts: 7

Hey all!! first post here. I'm a college Junior at the University of Texas. I'm an economics major and a business minor and have to take 2 more semesters of calculus. I'm currently taking M408L here. Got a few questions on definate integrals. Hope to stay here a while and learn and hopefully help out when I can Wink

for 16 i got #5

and for 18 i got #2

thx!

**Posted:** Sun Sep 18, 2005 10:27 am

Jimmy · Yang-Mills Theory Offline Joined: 03 Oct 2004 Posts: 920

You got them both:

1) Let $u=2x$ , then we have $4\int_0^3 f(2x) \ dx = 2\int_0^6 f(u) \ du = 2(8) = 16$

2) Let $u = 5-t^3 \Rightarrow du = -3t^2 \ dt$ , and then we have $-\frac{1}{3}\int \sin u \ du = \frac{\cos(5-t^3)}{3} + C$

**Posted:** Tue Sep 20, 2005 12:31 pm