Anyone know how to do integrations?

Question

i'm doing a review in class from last semester, and i can't get these 3 problems...

1) integral: 7r * 8^r dr

2) integral: ln(y)/sqrt(y) dy.....upper limit= 81, lower limit=16

3) integral: dx/(5-2x)

Answer 1

1) (7 8^r (-1 + r Ln[8]))/Ln[8]^2

2) 2 Sqrt[y] (-2 + Ln[y]) evaluated between these limits gives you

-20-8ln(16)+18ln(81)

3) -1/2 ln(5-2x)

Answer 2

1. I would first try integration by parts to eliminate the 7r and go from there

2. Use integration by parts again and your ln(y) will turn into 1/y, then combine the powers and do a simple integration from there

3. Use a u-substitution where u=5-2x, to get 1/2 int(du/u).