I have a test tomorrow and i really need to get these answers. 1. The streets of a city are laid out in a rectangular grid, that is 7 by 4. The 7 squares are the base and the 4 are the height. A)How many routes begin with 3 north steps in a row? The book has 8 and i can count 8 ways but i dont know how to get it. 2. The expansion of (3/x - x^3)^8 find a) The constant term b)The term containing x^12 For a) i did this: C(8,r) x (3/x)^8-r x (-x^3)^r I can't remember how to do it with a 3 as the top number. i cant add the exponents unless they have the same base so how do i do this. For b is there an easy way to figure out which has x^12 which actually doing the whole expanding. 3. Use the binomial Theorem to determine the expansion of (a + b + c)^3 I have three terms how do i solve this.