Question

HELPPPP!

You have checked out b books from the library, where b is a number greater than 5. You plan to read three of the books and return them at the end of this week. In how many ways can you pick the books you will read first, second, and third?

the choices are

A. b3 ways

B. b3- 3b2 + 2b ways

C. b3 - 9b2 + 27b - 27 ways

D. 5b - 3 ways

Answer 1

There are b choices for the first book, b-1 for the second, and b-2 for the third


So multiply b(b-1)(b-2) to get your answer

Answer 2

So what is (b-1)(b-2) ???

Answer 3

Do you know how to multiply (b-1)(b-2) out?

Answer 4

no

Answer 5

Alright, expand

(b-1)(b-2)

to get

b(b-2) - 1(b-2)

Answer 6

So what is b(b-2)

Answer 7

i have NO idea

Answer 8

do you know how to distribute?

Answer 9

NO i just started this and can not open my study guide i do online math for seniors

Answer 10

Basically, if you have something like

2(3+4)

you can rewrite it as

2*3 + 2*4

by using distribution

Answer 11

You multiply whatever is on the outside by everything on the inside and you add

Answer 12

whati'm not understanding is the letters?

Answer 13

well say we didn't know that term on the outside was a 2 and was some unknown number (say x), then we can say

x(3+4)

becomes

3x+4x

Answer 14

We can even say

x(x+5)

becomes

x*x + 5x

Answer 15

Does that make sense so far?

Answer 16

ok so what i'm getting is 5b - 3

Answer 17

b(b-2)

becomes

b*b - b*2

which then turns into

b^2 - 2b

Answer 18

- 1(b-2)

distributes out to

-b + 2

Answer 19

So

b(b-2) - 1(b-2)

becomes

b^2 - 2b - b + 2

Answer 20

Then we combine like terms to get b^2 - 3b + 2

Answer 21

ok so its b3 - 3b2 + 2b

Answer 22

Yes, you got it