Given the quadratic equation below, determine which it could represent.
x^2-4x=60

a: a wall in liza's bedroom has an area of 60 square feet. she covers 4 square feet of the wall with a poster.
b: on tuesday, a packaging company packed 4 fewer boxes of cashews than they did on monday. they packed a total of 60 boxes.
c: in a meeting room for a business event, there are 4 fewer chairs laid out in each row than the number of rows. the total number of chairs in the room is 60.
d: mr. bass is 4 years older than his sister. the total of their ages is 60 years.

Suppose we have a set of small wooden blocks showing the 26 letters of the english alphabet, one letter per block. (think of scrabble tiles.) our set includes 10 copies of each letter. we place them into a bag and draw out one block at a time. (a) if we line up the letters on a rack as we draw them, how different ways coukl we fill a rack of 5 letters? (b) now suppose we just toss our chosen blocks into a pile, and whenever we draw a letter we already have, we put it back in the bag and draw again. how many different piles of 5 blocks could result? possible? piles will contain at least one repeated letter? (c) if we draw out 5 blocks wit hout looking at them, how many different piles are (d) if we draw out 5 blocks without looking at them, how many of the possible 2. (4) consider the following formula. 12 give two different proofs, one using the factorial formulas and the other combina torial.